The elasticity of supply
Definition: the responsiveness of the quantity supplied to a small change in price. It is measured by:
%∆Qs / %∆P
The measure roughly indicates the slope of the supply curve; the steeper the more inelastic. Why is this only “roughly”? Because it depends on the scale of the diagram - for instance both the diagrams below have the same elasticity, but because the horizontal scale is not the same the slopes look differ- ent. That is why we have to draw two different elasticities on the same diagram where the scale is the same.
BUT unit elastic supply is any straight line that cuts through the origin! (Just remember this, and do not worry! If you are a mathematician, you may already see why.)
Supply periods and time: (covered briefly earlier)
Very short run = totally inelastic supply = fixed supply (e.g., the amount in a wholesale vegetable market delivered each morning; all the works of dead painters or sculptors).
Short run = perhaps moderately inelastic.
Long run = more elastic; or even negative elasticity (it slopes downward).
Why is supply more elastic in the long run?
Because the company can alter both the fixed and variable factors (i.e., all the factors of production). It can also find new or cheaper sources of raw materials; improve the training of labour; and introduce new technology or better machines. This allows the company to obtain more output without needing much increase in price.
The downward sloping supply curve in the long run is already familiar to you: computers, scanners, TV sets, digital cameras, DVD players and discs, CD players and discs….. Most if not all of the prod- ucts of modern hi-tech industry fall into this category. As the years go by, they get better and a lot cheaper.
Elasticity of supply is probably a bit less interesting to economists than the elasticities of demand - and it is easier to learn as there is less of it!
Tuesday 13 March 2012
Elasticity of demand
The elasticity of demand
ELASTICITIES
Elasticities are a sort of measure of supply and demand.
If demand increases, and we ask how much does supply extend, we need more than an answer like "quite a lot"!! Government may be trying to raise tax to get a certain amount of revenue for instance. The question is “How much will quantity change, a lot or a little?”
WE START WITH THE ELASTICITY OF DEMAND
Three broad types of elasticity of demand
1. Price elasticity = the usual one, it deals with 1 good.
2. Cross elasticity = a special one, it deals with 2 goods.
3. Income elasticity = a special one and it deals with changes in incomes.
1. Price Elasticity of Demand
Definition: "Price elasticity of demand is a measure of the responsiveness of the quantity demanded to a small change in price". Learn this by heart!
[In simpler terms, “is the proportional change in quantity greater or lesser than the change in price?”
As an example, if the price was 20 and it falls by 2, the fall is 10% (2 times 100, all divided by 20); and if quantity then increases from 100 to 200, the increase is 100%.
We can see that the increase in Q is greater (100% compared with 10%) - i.e., it stretches out a lot - it is elastic!]
How do we actually measure price elasticity?
Price elasticity of demand is measured by the percentage change in Qd, divided by the percentage change in price:
%∆Qd / %∆P
So the price elasticity of demand is:
[∆Q/Q] / [∆P/P]
→ ∆Q/Q x P/∆P (to divide by fraction invert and multiply)
→ ∆Q/∆P x Q/P (gathering the change terms all on side for neatness. If this shuffling makes you unhappy, just remember that 3 x 4 is the same as 4 x 3)
In the example above, the percentage change in Q was 100 and the percentage change in price was 10 so the elasticity is 100 divided by 10 = 10.0 In the world in which we live this is actually very high! (Anything over 2 in the real world is pretty high.)
Logically the answer can have only 1 of 3 results: <1, = 1, or >1
(< stands for “less than”; > stands for “more than”; if we are looking at “<” left to right, the way we read, we see it goes little to big so it is easy to remember!)
When we look at the fraction, we find that the answer is less than 1 if the top is smaller than the bottom, equal to 1 if the top and bottom are the same, or more than 1 if the top is greater than the bottom.
What does each possible answer mean?
a] If the answer is greater than 1 (e.g., 1.62) the demand curve is elastic.
It means that a small change in price led to big change in quantity (Q stretched a lot which means that it is elastic); graphically the curve tends to look flat when compared with an inelastic curve. But remember all curves must have the same scale and axis or else be on the same diagram.
Examples of demand curves which are price elastic:
Dell computers (one brand of many substitutes); foreign travel by cheap airlines.
b] If the answer is less than 1, e.g., 0.75, the demand curve is inelastic People do not respond so much to price cuts and although they buy more, they do not buy a lot more.
Examples:
Salt, bread, sets of cutlery (essentials; no substitutes).
c] If the answer just happens to equal 1 it is “unit elastic” (unity = 1), a special case and rarely seen, except perhaps for a small part of a large demand curve! The answer would work out at exactly 1.0 and the curve is asymptotic; this means that it approaches more and more closely but never quite reaches the axes.
Reminder: if you draw one rather flat demand curve in one diagram, demand is actually only relatively elastic etc because we do not know the scale - don’t worry about it, it’s technical! Just remember to say “relatively inelastic” or “relatively elastic” in the exam room! If you draw them on one diagram then you are on safer ground if you just say “elastic”.
What do the different elasticity demand curves look like?
The importance of the elasticity concept
It allows us to get precise answers, not be vague.
We need it for certain questions e.g., if a hairdresser is considering increasing her price for a basic cut from
£20 to £25, will profits rise or fall?
What determines price elasticity?
· The number of substitutes - the greater the substitutes, the more elastic the good - a small price rise means consumers switch to another brand. THIS IS THE MAIN DETERMINANT!
· The proportion of income - the greater the proportion of income going on good, the more elastic it tends to be. Salt is relatively inelastic and very cheap - would you consume a £2’s worth a year?
· Luxuries and necessities - luxuries tend to be more elastic (airfares, foreign travel); necessities more inelastic (electricity). Some economists do not like this “luxuries” point because what constitutes a luxury alters too much and in addition they can be personal to different individuals.
· Time - the longer the time, the more elastic demand tends to be, probably because
· More substitutes become available , the good or service is copied by others, new manufac- turers can enter, imports be made etc.
· Habits change only slowly, so we adjust to new prices slowly.
· Capital may need to wear out to make change, e.g., if the price of petrol rises, drivers have to wait until it is time to buy a new and smaller car in order to reduce petrol consumption.
Q. For the hairdresser earlier who is considering a price rise, I asked earlier what would happen to her profit if she charged more. Assume she is very good and her clients feel that there is no real substitute?
A. The demand curve for her services is inelastic so profit would rise!
Q. But consider what would happen if she were just another high street hair dresser? Draw the diagram for me now!
Another example of the importance of elasticity: if the government raises the tax on cigarettes, will government revenue rise or fall? And by how much?
The government normally wishes to raise more revenue - although there are health benefits if people reduce cigarette consumption, which saves on National Health Service expenditure too.
If the government raises tax by 5% and demand is inelastic, the quantity will fall as price rises, but it will fall by less than 5%, so revenue will increase.
If the government imposes an indirect tax, it pushes up the supply curve by the exact amount of tax.
If the tax is absolute e.g., £1 each item, it pushes the curve up parallel. The original producer faces no change in supply conditions, but £1 is added to each quantity.
When we draw the diagram for the imposition of indirect tax: we start at the original equilibrium, and add the tax.
When we look at the market equilibrium, we start with a supply and demand curve and see the original equilibrium. We then add the tax, which pushes up the supply curve and look at the new equilibrium position, to see what changes the tax has made.
We can see that the original equilibrium position P1Q1 becomes P2Q2 once the tax is imposed. There is a rise in price - but by less than the whole tax - and there is a fall in quantity.
The increase in tax per unit is AC, but the price only goes from P1 to P2 = BC; and BC is less than AC (price rises but by less than the whole amount of tax per unit)
What about the change in government revenue? This is the quantity now sold (OQ2 at the new equilibrium position = the number of units) times the tax per unit (AC). This is the area bounded by P2CAP3 in the diagram below.
If the indirect tax is ad valorem (proportional not absolute, e.g., 10%) it pushes up the supply curve at an increasing rate
Q. Why?
A. Because 10% of £1 is only 10P, but 10% of £10 is £1!
A subsidy is just a negative tax e.g., government gives producer some money (subsidy) rather than a producer or consumer giving money to the government (tax).
Subsidy questions are not usually as interesting as tax ones!
Let’s draw the diagram for putting on a subsidy.
We start, as ever, in the initial equilibrium position, P1Q1 on the curves S1 and D1. The subsidy goes on, the size of it is P1 to P2, and the new supply curve is S2. You can see that the unchanged quantity, Q1, is now cheaper at price P2- but we have not yet examined the new equilibrium position to see the results of the change.
What is the total amount of the subsidy, i.e., the cost to the government? We need to look at the new equilibrium position, which will be at P2Q2, below.
The subsidy is AB for each unit in the diagram above. The quantity sold after the subsidy is imposed is OQ2.
So how much does the subsidy cost the government, and ultimately the tax payer?
The subsidy the government pays is the new quantity sold, (0Q2) times the subsidy amount per unit of
BA.
We know that BA is the same as CD because the curve shifts parallel.
We know that the suppliers continue with curve S1, so they require price 0P3 for quantity 0Q2 (Note that the supplier works off the original supply curve - there has been no change in the determinants of his or her supply.)
We see that consumers pay the rectangle 0Q2CP2.
We see that the government pays the rectangle P2CDP3 - this is the subsidy cost to the tax payer. And together these add up to the total expenditure of 0Q2DP3.
Notice also that consumption rises from 0Q1 to 0Q2 - which is the point of the subsidy: more is pro- duced and consumed.
The limits of price elasticity of demand
Perfectly elastic = a horizontal line; this means that consumers will demand an infinite amount at that price! It is merely a limit and obviously it cannot be reached.
Perfectly inelastic = vertical line; this means that consumers will pay any amount at all, such as £1, or £1 million, or £1 trillion…. to buy the good or service. Again this is unreasonable, it’s merely a limit. They look like this:
2. Cross Elasticity of Demand
Definition: "Cross elasticity of demand is a measure of the responsiveness of the quantity demanded of one good or service to a small change in price of another". Learn this! It is virtually the same as the definition of price elasticity earlier - go on, compare them now!
Cross elasticity measures substitutes and complements (note the spelling; it is not “compliments”)
If the supply of beef increases so the equilibrium price falls, it may induce some people to switch from eating chicken or pork to eating the now cheaper beef. The fall in price of beef causes a decrease in quantity demanded of chicken or pork.
%∆Qd of good A / %∆P of good B
Note the “A” and “B” difference: we are dividing the percentage change in the quantity of A by the change in the price of B.
If the price of beef fell and the quantity of chicken fell the answer will be positive, because two negatives make a positive, so any items with a positive cross elasticity are substitutes.
If the price of heating oil falls it may induce some to install oil generated central heating in houses. We see that a fall in the price of A means an increase in the quantity of generators, so the answer is nega- tive (one plus and one minus) so these two goods are complements.
Cross elasticity does not seem to be used much in economics, except in exams.
3. Income Elasticity of Demand
Now this is most important! Incomes keep increasing over time, so the demand pattern for various goods and services keeps changing. This matters for new firms looking to move into the market and produce something: the market for what goods or services is likely to grow the fastest? That’s the area to be in! It matters for existing firms looking to diversify, or be concerned about the prospects for the future in the area they produce and sell in.
Definition: "Income elasticity of demand is a measure of the responsiveness of the quantity demanded of a good or service to a small change in income". Learn!
Income elastic: a given change in income leads to a greater than proportionate increase in demand for the good or service. Examples of income elastic goods: foreign travel, good wines, smart motor cars, eating in restaurants, and currently well-regarded brands, e.g., Adidas sportswear or Rolex watches.
Income inelastic: a given change in income leads to a less than proportionate increase in demand for the good or service. Examples: bread, staple foods generally, cheap stores, and all lowly-regarded brands. If our income happens to double (lucky us!) we do not spend twice as much on such items.
Income neutral elastic: should it just happen that, say, a 5% increase in income leads to a 5% increase in demand for a good or service, then it is income neutral elastic. This is not really an interesting case, merely a bit strange. Oddly enough, Pizza Hut in Australia claimed in the 1990s that they were like this: in a recession some people stopped eating out so stopped going to Pizza Hut, but other people switched from “proper” restaurants to Pizza Hut which cancelled things out, so the company did not suffer!
Income negative elastic: this is most interesting! This happens when an increase in income causes a fall in demand. Really it indicates that we dislike this product but for some reason we must consume it at
the time. When we can afford not to consume it, then we stop buying it. Examiners like this concept!
Examples are scarce, but it is suggested that probably potatoes were like this in Ireland during the Nine- teenth century. Currently, the demand for mealies (sweet corn) in some African countries may be in- come negative elastic. It is a rare event anyway. Negative income elasticity means that it is an “inferior good”.
ELASTICITIES
Elasticities are a sort of measure of supply and demand.
If demand increases, and we ask how much does supply extend, we need more than an answer like "quite a lot"!! Government may be trying to raise tax to get a certain amount of revenue for instance. The question is “How much will quantity change, a lot or a little?”
WE START WITH THE ELASTICITY OF DEMAND
Three broad types of elasticity of demand
1. Price elasticity = the usual one, it deals with 1 good.
2. Cross elasticity = a special one, it deals with 2 goods.
3. Income elasticity = a special one and it deals with changes in incomes.
1. Price Elasticity of Demand
Definition: "Price elasticity of demand is a measure of the responsiveness of the quantity demanded to a small change in price". Learn this by heart!
[In simpler terms, “is the proportional change in quantity greater or lesser than the change in price?”
As an example, if the price was 20 and it falls by 2, the fall is 10% (2 times 100, all divided by 20); and if quantity then increases from 100 to 200, the increase is 100%.
We can see that the increase in Q is greater (100% compared with 10%) - i.e., it stretches out a lot - it is elastic!]
How do we actually measure price elasticity?
Price elasticity of demand is measured by the percentage change in Qd, divided by the percentage change in price:
%∆Qd / %∆P
So the price elasticity of demand is:
[∆Q/Q] / [∆P/P]
→ ∆Q/Q x P/∆P (to divide by fraction invert and multiply)
→ ∆Q/∆P x Q/P (gathering the change terms all on side for neatness. If this shuffling makes you unhappy, just remember that 3 x 4 is the same as 4 x 3)
In the example above, the percentage change in Q was 100 and the percentage change in price was 10 so the elasticity is 100 divided by 10 = 10.0 In the world in which we live this is actually very high! (Anything over 2 in the real world is pretty high.)
Logically the answer can have only 1 of 3 results: <1, = 1, or >1
(< stands for “less than”; > stands for “more than”; if we are looking at “<” left to right, the way we read, we see it goes little to big so it is easy to remember!)
When we look at the fraction, we find that the answer is less than 1 if the top is smaller than the bottom, equal to 1 if the top and bottom are the same, or more than 1 if the top is greater than the bottom.
What does each possible answer mean?
a] If the answer is greater than 1 (e.g., 1.62) the demand curve is elastic.
It means that a small change in price led to big change in quantity (Q stretched a lot which means that it is elastic); graphically the curve tends to look flat when compared with an inelastic curve. But remember all curves must have the same scale and axis or else be on the same diagram.
Examples of demand curves which are price elastic:
Dell computers (one brand of many substitutes); foreign travel by cheap airlines.
b] If the answer is less than 1, e.g., 0.75, the demand curve is inelastic People do not respond so much to price cuts and although they buy more, they do not buy a lot more.
Examples:
Salt, bread, sets of cutlery (essentials; no substitutes).
c] If the answer just happens to equal 1 it is “unit elastic” (unity = 1), a special case and rarely seen, except perhaps for a small part of a large demand curve! The answer would work out at exactly 1.0 and the curve is asymptotic; this means that it approaches more and more closely but never quite reaches the axes.
Reminder: if you draw one rather flat demand curve in one diagram, demand is actually only relatively elastic etc because we do not know the scale - don’t worry about it, it’s technical! Just remember to say “relatively inelastic” or “relatively elastic” in the exam room! If you draw them on one diagram then you are on safer ground if you just say “elastic”.
What do the different elasticity demand curves look like?
The importance of the elasticity concept
It allows us to get precise answers, not be vague.
We need it for certain questions e.g., if a hairdresser is considering increasing her price for a basic cut from
£20 to £25, will profits rise or fall?
What determines price elasticity?
· The number of substitutes - the greater the substitutes, the more elastic the good - a small price rise means consumers switch to another brand. THIS IS THE MAIN DETERMINANT!
· The proportion of income - the greater the proportion of income going on good, the more elastic it tends to be. Salt is relatively inelastic and very cheap - would you consume a £2’s worth a year?
· Luxuries and necessities - luxuries tend to be more elastic (airfares, foreign travel); necessities more inelastic (electricity). Some economists do not like this “luxuries” point because what constitutes a luxury alters too much and in addition they can be personal to different individuals.
· Time - the longer the time, the more elastic demand tends to be, probably because
· More substitutes become available , the good or service is copied by others, new manufac- turers can enter, imports be made etc.
· Habits change only slowly, so we adjust to new prices slowly.
· Capital may need to wear out to make change, e.g., if the price of petrol rises, drivers have to wait until it is time to buy a new and smaller car in order to reduce petrol consumption.
Q. For the hairdresser earlier who is considering a price rise, I asked earlier what would happen to her profit if she charged more. Assume she is very good and her clients feel that there is no real substitute?
A. The demand curve for her services is inelastic so profit would rise!
Q. But consider what would happen if she were just another high street hair dresser? Draw the diagram for me now!
Another example of the importance of elasticity: if the government raises the tax on cigarettes, will government revenue rise or fall? And by how much?
The government normally wishes to raise more revenue - although there are health benefits if people reduce cigarette consumption, which saves on National Health Service expenditure too.
If the government raises tax by 5% and demand is inelastic, the quantity will fall as price rises, but it will fall by less than 5%, so revenue will increase.
If the government imposes an indirect tax, it pushes up the supply curve by the exact amount of tax.
If the tax is absolute e.g., £1 each item, it pushes the curve up parallel. The original producer faces no change in supply conditions, but £1 is added to each quantity.
When we draw the diagram for the imposition of indirect tax: we start at the original equilibrium, and add the tax.
When we look at the market equilibrium, we start with a supply and demand curve and see the original equilibrium. We then add the tax, which pushes up the supply curve and look at the new equilibrium position, to see what changes the tax has made.
We can see that the original equilibrium position P1Q1 becomes P2Q2 once the tax is imposed. There is a rise in price - but by less than the whole tax - and there is a fall in quantity.
The increase in tax per unit is AC, but the price only goes from P1 to P2 = BC; and BC is less than AC (price rises but by less than the whole amount of tax per unit)
What about the change in government revenue? This is the quantity now sold (OQ2 at the new equilibrium position = the number of units) times the tax per unit (AC). This is the area bounded by P2CAP3 in the diagram below.
If the indirect tax is ad valorem (proportional not absolute, e.g., 10%) it pushes up the supply curve at an increasing rate
Q. Why?
A. Because 10% of £1 is only 10P, but 10% of £10 is £1!
A subsidy is just a negative tax e.g., government gives producer some money (subsidy) rather than a producer or consumer giving money to the government (tax).
Subsidy questions are not usually as interesting as tax ones!
Let’s draw the diagram for putting on a subsidy.
We start, as ever, in the initial equilibrium position, P1Q1 on the curves S1 and D1. The subsidy goes on, the size of it is P1 to P2, and the new supply curve is S2. You can see that the unchanged quantity, Q1, is now cheaper at price P2- but we have not yet examined the new equilibrium position to see the results of the change.
What is the total amount of the subsidy, i.e., the cost to the government? We need to look at the new equilibrium position, which will be at P2Q2, below.
The subsidy is AB for each unit in the diagram above. The quantity sold after the subsidy is imposed is OQ2.
So how much does the subsidy cost the government, and ultimately the tax payer?
The subsidy the government pays is the new quantity sold, (0Q2) times the subsidy amount per unit of
BA.
We know that BA is the same as CD because the curve shifts parallel.
We know that the suppliers continue with curve S1, so they require price 0P3 for quantity 0Q2 (Note that the supplier works off the original supply curve - there has been no change in the determinants of his or her supply.)
We see that consumers pay the rectangle 0Q2CP2.
We see that the government pays the rectangle P2CDP3 - this is the subsidy cost to the tax payer. And together these add up to the total expenditure of 0Q2DP3.
Notice also that consumption rises from 0Q1 to 0Q2 - which is the point of the subsidy: more is pro- duced and consumed.
The limits of price elasticity of demand
Perfectly elastic = a horizontal line; this means that consumers will demand an infinite amount at that price! It is merely a limit and obviously it cannot be reached.
Perfectly inelastic = vertical line; this means that consumers will pay any amount at all, such as £1, or £1 million, or £1 trillion…. to buy the good or service. Again this is unreasonable, it’s merely a limit. They look like this:
2. Cross Elasticity of Demand
Definition: "Cross elasticity of demand is a measure of the responsiveness of the quantity demanded of one good or service to a small change in price of another". Learn this! It is virtually the same as the definition of price elasticity earlier - go on, compare them now!
Cross elasticity measures substitutes and complements (note the spelling; it is not “compliments”)
If the supply of beef increases so the equilibrium price falls, it may induce some people to switch from eating chicken or pork to eating the now cheaper beef. The fall in price of beef causes a decrease in quantity demanded of chicken or pork.
%∆Qd of good A / %∆P of good B
Note the “A” and “B” difference: we are dividing the percentage change in the quantity of A by the change in the price of B.
If the price of beef fell and the quantity of chicken fell the answer will be positive, because two negatives make a positive, so any items with a positive cross elasticity are substitutes.
If the price of heating oil falls it may induce some to install oil generated central heating in houses. We see that a fall in the price of A means an increase in the quantity of generators, so the answer is nega- tive (one plus and one minus) so these two goods are complements.
Cross elasticity does not seem to be used much in economics, except in exams.
3. Income Elasticity of Demand
Now this is most important! Incomes keep increasing over time, so the demand pattern for various goods and services keeps changing. This matters for new firms looking to move into the market and produce something: the market for what goods or services is likely to grow the fastest? That’s the area to be in! It matters for existing firms looking to diversify, or be concerned about the prospects for the future in the area they produce and sell in.
Definition: "Income elasticity of demand is a measure of the responsiveness of the quantity demanded of a good or service to a small change in income". Learn!
Income elastic: a given change in income leads to a greater than proportionate increase in demand for the good or service. Examples of income elastic goods: foreign travel, good wines, smart motor cars, eating in restaurants, and currently well-regarded brands, e.g., Adidas sportswear or Rolex watches.
Income inelastic: a given change in income leads to a less than proportionate increase in demand for the good or service. Examples: bread, staple foods generally, cheap stores, and all lowly-regarded brands. If our income happens to double (lucky us!) we do not spend twice as much on such items.
Income neutral elastic: should it just happen that, say, a 5% increase in income leads to a 5% increase in demand for a good or service, then it is income neutral elastic. This is not really an interesting case, merely a bit strange. Oddly enough, Pizza Hut in Australia claimed in the 1990s that they were like this: in a recession some people stopped eating out so stopped going to Pizza Hut, but other people switched from “proper” restaurants to Pizza Hut which cancelled things out, so the company did not suffer!
Income negative elastic: this is most interesting! This happens when an increase in income causes a fall in demand. Really it indicates that we dislike this product but for some reason we must consume it at
the time. When we can afford not to consume it, then we stop buying it. Examiners like this concept!
Examples are scarce, but it is suggested that probably potatoes were like this in Ireland during the Nine- teenth century. Currently, the demand for mealies (sweet corn) in some African countries may be in- come negative elastic. It is a rare event anyway. Negative income elasticity means that it is an “inferior good”.
Demand and Supply
Demand and supply: An introduction
(Abbreviations: S = “supply”; D = “demand”; Y = “income”; r = “rate of interest”)
At the equilibrium price, the quantity demanded just equals the quantity supplied. There are unsatisfied con- sumers who could not buy at that price even though they were willing. What do we mean by equilibrium? Equilibrium is the state of affairs in which there is no tendency to change. How do we show this equilibrium price? We use demand and supply curves.
Demand
What is the demand curve? It is a curve showing the quantity that will be bought on the market at different prices.
The lower the price, the more will be demanded; the higher the price the less will be demanded. Think! If all Nike trainers were £2 a pair, would you buy more than if they were £200 a pair? It seems probable!
In economics, “demand” means demand is backed by money – it is not just a need or a desire, but people do have the money to buy and are prepared to buy.
Supply
What is the supply curve? The supply curve is a curve showing the quantity that will be offered on the mar- ket at different prices. We believe that higher prices cause more people to sell. Imagine: in your classroom,
if I offer to buy each T shirt for £500, almost everyone will sell to me; but if I offer £1 each, probably few if any would be willing If however I were to offer £7, more would sell but probably not everyone. That is why the supply curve slopes upward.
Let’s put both the demand and supply curves on the same diagram .
Guess where the equilibrium price will be? Right! Where the two curves cross! As said earlier, at the equi- librium price, the quantity demanded just equals the quantity supplied. There are no unsatisfied consumers who could not buy at that price even though they were willing and everyone who wanted to sell at that price could do so. This happy situation happens at the intersection of D and S with price P and quantity Q.
When I started in economics, I had to chant along with the rest of the class: "price is determined by supply and demand!” It certainly made it stick in my mind and might help you too!
Let us return and look at demand in more detail (We’ll look at supply later too)
What determines the D curve?i.e., why is it where it is and not somewhere else?
1. There are four main personal determinants of demand
· Income
· Taste
· Prices of other goods or service
· Expectations about future prices of this good or service
2. AND several other market determinants
· Income distribution - if you think of all the other people in your house and you as you are now, then if you suddenly got all the total income and savings and the others had none, there would be a dif- ferent pattern of demand from what it is now. They probably do not eat lunch every day if they have no money. It is the same in society in general: change the income distribution and a new pattern of demand curves follows.
· Wealth distribution (as opposed to income distribution). If 10% of the population have 90% of the wealth, probably more Porsche motor cars will be demanded than if we all have the same rather lowish amount!
· Population size - the larger the population, the bigger the demand, ceteris paribus. That is a Lat- in tag meaning “all other things remaining the same” and you might come across it in a lot of eco- nomics books.
· Population age distribution - if there are many old people, important demands in society will be for medicines, hip replacement operations and Zimmer frames but fewer Beastie Boys CDs, or prams.
· The interest rate. This is especially important for house purchases, motor cars, long-life consumer goods often on a credit card, or hire purchase generally. A higher rate of interest means more to re- pay, so people tend to borrow less.
What can cause a shift in the demand curve? (= a new curve)
A change in any of the above determinants of demand will do it!
If demand increases, overall, more of the good/service is bought at any unchanged (the same) price. You can see this in the diagram below, where at P1 an amount OQ1 is demanded, but after demand increases to D2,
at the same price an large amount is demanded, i.e., OQ2. It is easy to remember what “an increase in de- mand” means; there must be a new curve and it will move upwards and to the right.
The effects of an increase in demand are usually analysed using the equilibrium positions determined by the intersection of demand and supply.
You can see that the increase in demand means we move from the equilibrium position P1Q1 to the new equilibrium position P2Q2. More is demanded - we shift from the position Q1 to the position Q2, so the dif- ference (OQ2 minus OQ1) is Q1Q2.
The way the diagram of a shift in demand is drawn,(shown not moving to the new equilibrium, so you can see that more is demanded at the same price)
The way the diagrams are built up should be reasonably clear by now. If you have any worries, check back and examine those supplied earlier. The general principles are:
1. Draw the axes and label them immediately (“one axis, two axes”).
2. Put in the first curve and label it.
3. Add the second curve and label it.
4. Draw the equilibrium position – preferably using dotted lines.
5. Make the necessary changes, such as shift a curve inwards or outwards by drawing a new curve and la- belling it.
6. Draw the new equilibrium position – preferably using dotted lines.
7. And finally you compare the new equilibrium position with the first one, using your own words but trying to get in the necessary jargon phrases such as “increase in demand”, or “economic growth”, whatever is relevant to the question you are tackling.
Henceforth I shall not be supplying the series of pictures showing how the diagrams are built up, as you should be able to follow the above principles for yourself. Before long, it will become second nature to ex-amine a finished diagram and work out how it was built up.
If demand decreases, the demand curve shifts the other way, downward and to the left. Again we have a new curve, as in the diagram below.
You will notice that less is bought at any given price, such as P.
Again, a decrease in demand is usually analysed by determining the new equilibrium position and the com- paring it with the original one. For this we need to put the supply curve in.
As you can see, if demand decreases, then less is bought (as you might imagine!) and the quantity demanded falls from Q2 to Q1; price also falls, in this case from P1 to P2
Let us look at supply in more detail
What determines the supply curve, i.e. why is it where it is and not somewhere else?
The answer is, the price, quantity, and quality of inputs used. These consist of things like machinery, equipment, staff and workers, raw materials, and fuel. These are collectively known as “the factors of production”, and are often summarised as land, (L) labour (N) and capital (K) plus a remainder term, R.
· Land - is what it says but can include things like diamonds or oil that are found there.
· Labour mostly means workers, but also includes managers.
· Capital means machinery and equipment. A subset of this is“social overhead capital” - like roads, bridges and docks.
[Digression: The whole production of the nation can be summed up as: O = f(L, N, K) + R
or put into words, “output is a function of (= is in some as yet undefined way caused by) land, labour, capi- tal, and a few other things”. You will need this later; I am just sowing a few seeds.]
· The remainder term “R”, which covers things in both labour and capital is the really interesting one
The labour component of “R”. This consists of things like entrepreneurial ability, the managerial methods in use, labour motivation and how good it is, labour skills, the strength of the trade union and its attitudes, the bonus and other incentive systems in force, the quality of the education system, and the retraining facilities available in society.
The capital component of “R”. This consists of things like:
The level of technology, knowledge about what technology is available, the adequacy of factory organi- sation, and economies of scale. They can obviously affect the supply curve, or the output possible, if they are good or bad.
· Maybe the weather, e.g. floods can destroy crops, effect transport, reduce supply, and raise price.
· Joint supply - if we increase the number of sheep to supply an increased demand for mutton, it auto- matically increases the wool supply. So the price of related good can be a determinant of supply. Examiners like questions on joint supply, but it is not often encountered in the world in which we live.
· The productivity of the factors of production – this is closely related to technology; but it can also be how hard workers are prepared to work, motivation, and incentives systems etc. (it too can appear separately, or be included in the remainder term, R, as above).
· The size and number of firms in the industry, including the marketing conditions.
· War and social unrest.
What can cause an increase or decrease in supply?(a shift in the curve)
Like demand, it needs a change in one or more of the determinants. For supply these include things like:
· A change in the price of a factor of production.
· A change in the productivity of a factor.
· New technology invented.
· The discovery of a new raw material or fuel.
· More worker enthusiasm. This occurs often in war time, because of patriotism.
An increase in supply = the curve shifts downward and to the right (more is supplied at the unchanged price) - e.g., if labour productivity increases or someone finds a new cheap source of materials.
You will notice that the quantity supplied at the unchanged price P1 increases - well, that’s what an increase in supply does!
And if we put in a demand curve we can see both the equilibrium positions and work out that an increase in supply means a fall in price and an increase in the quantity purchased.
Time Periods And Supply
Three time periods matter:
· the very short run (VSR) (or “momentary supply”),
· the short run (SR) , and
· the long run (LR).
They have different slopes to their curves and different elasticities (more later!).
The very short run. This is defined as the time when no change can be made in any of the factors of produc- tion – the supply curve is vertical. Examples are the fruit and vegetables that appear in the wholesale market each day.
The short run.
This is defined as the period in which the variable factors can be altered but not the fixed factors, i.e. we can make some changes.
· Fixed factors = those that do not vary with output such as factory building, transport fleet, office staff, and the bill for heating and lighting the premises.
· Variable factors = those that vary directly with output such as raw materials, the energy used, the petrol in the trucks, and the wages of some unskilled workers who might be taken on when needed, perhaps part-time.
The supply curve we usually draw is the short run one. The long run
Is defined as the period when all factors can be varied i.e., the producer can do any changes s/he wants. This means a flatter curve, possibly even downward sloping sometimes.
How the supply curve can vary with the time period we are considering:
The flatter the curve, the more elastic it is (“quantity stretches more”). Producers will only make changes that help them produce more or reduce costs.
NOTE that all the curves are drawn on the one diagram; this means the scale is the same for all; if you draw each in a separate diagram, the flatter one (S long run) is not necessarily the most elastic, as the horizontal axis might be on a much wider scale. If this seems incomprehensible to you, Do Not Worry! Just remember to put them all on the same diagram.
Remember that you should practise drawing the diagrams regularly!
Increases and Extensions of Supply And Demand
We know that the word "increase" means a shift of the curve – but what about extensions? "Extensions" are movements along an existing curve.
Questions are often set to see if you know the difference between an ”increase” and an “extension”.
[A digression: if a line crosses two others, an increase in one curve always means an extension of the other! The diagram here shows that.
We see two upward sloping lines that cross a single line. The upward sloping lines reflect an increase (or decrease) and we slide down (or up) the single line.
For supply and demand:
With an increase in demand we slide up an unchanged supply curve.
NOTE that we start on demand curve D1 and supply curve S1 to ascertain the equilibrium price and quantity; then we look at D2 to get the second equilibrium position.
Reminder: In economics, at this level we always start in equilibrium, then we alter something, and move to the new equilibrium position. We then compare the two equilibrium positions for the analysis.
And we can see an increase in supply goes with an extension of demand, as we slide down an unchanged demand curve:
Decreases and contractions of supply and demand
A decrease means a new curve, which shifts backwards; a contraction means sliding back along an un- changed curve.
A contraction of demand following a decrease in supply :
A contraction of supply following a decrease in demand:
Here is one of the hoary old trick questions. "Demand increases, so price rises. The rise in price means fewer can afford the good, so demand decreases and prices fall again." Do you agree with this statement?
Question: what do you think?
At first glance it might seem to make sense. But it is in fact false!
Why is it false? You draw the diagram now on a piece of paper. First increase the demand curve and you will see the price rise as we extend up the supply curve.
Then think about the new equilibrium. Why on earth should it change? It is an equilibrium position! That was why you learned the definition of equilibrium a little while ago - to be able to detect fallacies in argument.
This is a proposition in logic, designed to test if you really understand supply and demand. You should try to get the words “extension” and “increase” in to show you can use them properly and you definitely need a diagram.
(Abbreviations: S = “supply”; D = “demand”; Y = “income”; r = “rate of interest”)
At the equilibrium price, the quantity demanded just equals the quantity supplied. There are unsatisfied con- sumers who could not buy at that price even though they were willing. What do we mean by equilibrium? Equilibrium is the state of affairs in which there is no tendency to change. How do we show this equilibrium price? We use demand and supply curves.
Demand
What is the demand curve? It is a curve showing the quantity that will be bought on the market at different prices.
The lower the price, the more will be demanded; the higher the price the less will be demanded. Think! If all Nike trainers were £2 a pair, would you buy more than if they were £200 a pair? It seems probable!
In economics, “demand” means demand is backed by money – it is not just a need or a desire, but people do have the money to buy and are prepared to buy.
Supply
What is the supply curve? The supply curve is a curve showing the quantity that will be offered on the mar- ket at different prices. We believe that higher prices cause more people to sell. Imagine: in your classroom,
if I offer to buy each T shirt for £500, almost everyone will sell to me; but if I offer £1 each, probably few if any would be willing If however I were to offer £7, more would sell but probably not everyone. That is why the supply curve slopes upward.
Let’s put both the demand and supply curves on the same diagram .
Guess where the equilibrium price will be? Right! Where the two curves cross! As said earlier, at the equi- librium price, the quantity demanded just equals the quantity supplied. There are no unsatisfied consumers who could not buy at that price even though they were willing and everyone who wanted to sell at that price could do so. This happy situation happens at the intersection of D and S with price P and quantity Q.
When I started in economics, I had to chant along with the rest of the class: "price is determined by supply and demand!” It certainly made it stick in my mind and might help you too!
Let us return and look at demand in more detail (We’ll look at supply later too)
What determines the D curve?i.e., why is it where it is and not somewhere else?
1. There are four main personal determinants of demand
· Income
· Taste
· Prices of other goods or service
· Expectations about future prices of this good or service
2. AND several other market determinants
· Income distribution - if you think of all the other people in your house and you as you are now, then if you suddenly got all the total income and savings and the others had none, there would be a dif- ferent pattern of demand from what it is now. They probably do not eat lunch every day if they have no money. It is the same in society in general: change the income distribution and a new pattern of demand curves follows.
· Wealth distribution (as opposed to income distribution). If 10% of the population have 90% of the wealth, probably more Porsche motor cars will be demanded than if we all have the same rather lowish amount!
· Population size - the larger the population, the bigger the demand, ceteris paribus. That is a Lat- in tag meaning “all other things remaining the same” and you might come across it in a lot of eco- nomics books.
· Population age distribution - if there are many old people, important demands in society will be for medicines, hip replacement operations and Zimmer frames but fewer Beastie Boys CDs, or prams.
· The interest rate. This is especially important for house purchases, motor cars, long-life consumer goods often on a credit card, or hire purchase generally. A higher rate of interest means more to re- pay, so people tend to borrow less.
What can cause a shift in the demand curve? (= a new curve)
A change in any of the above determinants of demand will do it!
If demand increases, overall, more of the good/service is bought at any unchanged (the same) price. You can see this in the diagram below, where at P1 an amount OQ1 is demanded, but after demand increases to D2,
at the same price an large amount is demanded, i.e., OQ2. It is easy to remember what “an increase in de- mand” means; there must be a new curve and it will move upwards and to the right.
The effects of an increase in demand are usually analysed using the equilibrium positions determined by the intersection of demand and supply.
You can see that the increase in demand means we move from the equilibrium position P1Q1 to the new equilibrium position P2Q2. More is demanded - we shift from the position Q1 to the position Q2, so the dif- ference (OQ2 minus OQ1) is Q1Q2.
The way the diagram of a shift in demand is drawn,(shown not moving to the new equilibrium, so you can see that more is demanded at the same price)
The way the diagrams are built up should be reasonably clear by now. If you have any worries, check back and examine those supplied earlier. The general principles are:
1. Draw the axes and label them immediately (“one axis, two axes”).
2. Put in the first curve and label it.
3. Add the second curve and label it.
4. Draw the equilibrium position – preferably using dotted lines.
5. Make the necessary changes, such as shift a curve inwards or outwards by drawing a new curve and la- belling it.
6. Draw the new equilibrium position – preferably using dotted lines.
7. And finally you compare the new equilibrium position with the first one, using your own words but trying to get in the necessary jargon phrases such as “increase in demand”, or “economic growth”, whatever is relevant to the question you are tackling.
Henceforth I shall not be supplying the series of pictures showing how the diagrams are built up, as you should be able to follow the above principles for yourself. Before long, it will become second nature to ex-amine a finished diagram and work out how it was built up.
If demand decreases, the demand curve shifts the other way, downward and to the left. Again we have a new curve, as in the diagram below.
You will notice that less is bought at any given price, such as P.
Again, a decrease in demand is usually analysed by determining the new equilibrium position and the com- paring it with the original one. For this we need to put the supply curve in.
As you can see, if demand decreases, then less is bought (as you might imagine!) and the quantity demanded falls from Q2 to Q1; price also falls, in this case from P1 to P2
Let us look at supply in more detail
What determines the supply curve, i.e. why is it where it is and not somewhere else?
The answer is, the price, quantity, and quality of inputs used. These consist of things like machinery, equipment, staff and workers, raw materials, and fuel. These are collectively known as “the factors of production”, and are often summarised as land, (L) labour (N) and capital (K) plus a remainder term, R.
· Land - is what it says but can include things like diamonds or oil that are found there.
· Labour mostly means workers, but also includes managers.
· Capital means machinery and equipment. A subset of this is“social overhead capital” - like roads, bridges and docks.
[Digression: The whole production of the nation can be summed up as: O = f(L, N, K) + R
or put into words, “output is a function of (= is in some as yet undefined way caused by) land, labour, capi- tal, and a few other things”. You will need this later; I am just sowing a few seeds.]
· The remainder term “R”, which covers things in both labour and capital is the really interesting one
The labour component of “R”. This consists of things like entrepreneurial ability, the managerial methods in use, labour motivation and how good it is, labour skills, the strength of the trade union and its attitudes, the bonus and other incentive systems in force, the quality of the education system, and the retraining facilities available in society.
The capital component of “R”. This consists of things like:
The level of technology, knowledge about what technology is available, the adequacy of factory organi- sation, and economies of scale. They can obviously affect the supply curve, or the output possible, if they are good or bad.
· Maybe the weather, e.g. floods can destroy crops, effect transport, reduce supply, and raise price.
· Joint supply - if we increase the number of sheep to supply an increased demand for mutton, it auto- matically increases the wool supply. So the price of related good can be a determinant of supply. Examiners like questions on joint supply, but it is not often encountered in the world in which we live.
· The productivity of the factors of production – this is closely related to technology; but it can also be how hard workers are prepared to work, motivation, and incentives systems etc. (it too can appear separately, or be included in the remainder term, R, as above).
· The size and number of firms in the industry, including the marketing conditions.
· War and social unrest.
What can cause an increase or decrease in supply?(a shift in the curve)
Like demand, it needs a change in one or more of the determinants. For supply these include things like:
· A change in the price of a factor of production.
· A change in the productivity of a factor.
· New technology invented.
· The discovery of a new raw material or fuel.
· More worker enthusiasm. This occurs often in war time, because of patriotism.
An increase in supply = the curve shifts downward and to the right (more is supplied at the unchanged price) - e.g., if labour productivity increases or someone finds a new cheap source of materials.
You will notice that the quantity supplied at the unchanged price P1 increases - well, that’s what an increase in supply does!
And if we put in a demand curve we can see both the equilibrium positions and work out that an increase in supply means a fall in price and an increase in the quantity purchased.
Time Periods And Supply
Three time periods matter:
· the very short run (VSR) (or “momentary supply”),
· the short run (SR) , and
· the long run (LR).
They have different slopes to their curves and different elasticities (more later!).
The very short run. This is defined as the time when no change can be made in any of the factors of produc- tion – the supply curve is vertical. Examples are the fruit and vegetables that appear in the wholesale market each day.
The short run.
This is defined as the period in which the variable factors can be altered but not the fixed factors, i.e. we can make some changes.
· Fixed factors = those that do not vary with output such as factory building, transport fleet, office staff, and the bill for heating and lighting the premises.
· Variable factors = those that vary directly with output such as raw materials, the energy used, the petrol in the trucks, and the wages of some unskilled workers who might be taken on when needed, perhaps part-time.
The supply curve we usually draw is the short run one. The long run
Is defined as the period when all factors can be varied i.e., the producer can do any changes s/he wants. This means a flatter curve, possibly even downward sloping sometimes.
How the supply curve can vary with the time period we are considering:
The flatter the curve, the more elastic it is (“quantity stretches more”). Producers will only make changes that help them produce more or reduce costs.
NOTE that all the curves are drawn on the one diagram; this means the scale is the same for all; if you draw each in a separate diagram, the flatter one (S long run) is not necessarily the most elastic, as the horizontal axis might be on a much wider scale. If this seems incomprehensible to you, Do Not Worry! Just remember to put them all on the same diagram.
Remember that you should practise drawing the diagrams regularly!
Increases and Extensions of Supply And Demand
We know that the word "increase" means a shift of the curve – but what about extensions? "Extensions" are movements along an existing curve.
Questions are often set to see if you know the difference between an ”increase” and an “extension”.
[A digression: if a line crosses two others, an increase in one curve always means an extension of the other! The diagram here shows that.
We see two upward sloping lines that cross a single line. The upward sloping lines reflect an increase (or decrease) and we slide down (or up) the single line.
For supply and demand:
With an increase in demand we slide up an unchanged supply curve.
NOTE that we start on demand curve D1 and supply curve S1 to ascertain the equilibrium price and quantity; then we look at D2 to get the second equilibrium position.
Reminder: In economics, at this level we always start in equilibrium, then we alter something, and move to the new equilibrium position. We then compare the two equilibrium positions for the analysis.
And we can see an increase in supply goes with an extension of demand, as we slide down an unchanged demand curve:
Decreases and contractions of supply and demand
A decrease means a new curve, which shifts backwards; a contraction means sliding back along an un- changed curve.
A contraction of demand following a decrease in supply :
A contraction of supply following a decrease in demand:
Here is one of the hoary old trick questions. "Demand increases, so price rises. The rise in price means fewer can afford the good, so demand decreases and prices fall again." Do you agree with this statement?
Question: what do you think?
At first glance it might seem to make sense. But it is in fact false!
Why is it false? You draw the diagram now on a piece of paper. First increase the demand curve and you will see the price rise as we extend up the supply curve.
Then think about the new equilibrium. Why on earth should it change? It is an equilibrium position! That was why you learned the definition of equilibrium a little while ago - to be able to detect fallacies in argument.
This is a proposition in logic, designed to test if you really understand supply and demand. You should try to get the words “extension” and “increase” in to show you can use them properly and you definitely need a diagram.
Tuesday 6 March 2012
List of phobias
Complete Phobia List and their meanings: A
Ablutophobia - Fear of washing or bathing.
Acarophobia - Fear of itching or of the insects that cause itching.
Acerophobia - Fear of sourness.
Achluophobia - Fear of darkness.
Acousticophobia - Fear of noise.
Aeroacrophobia - Fear of open high places.
Aeronausiphobia - Fear of vomiting secondary to airsickness.
Aerophobia - Fear of drafts, air swallowing, or airborne noxious substances.
Agliophobia - Fear of pain.
Agoraphobia - Fear of open spaces or of being in crowded, public places like markets. Fear of leaving a safe place. Fear of crowds.
Agraphobia - Fear of sexual abuse.
Agrizoophobia - Fear of wild animals.
Agyrophobia - Fear of streets or crossing the street.
Aichmophobia - Fear of needles or pointed objects.
Ailurophobia - Fear of cats.
Albuminurophobia - Fear of kidney disease.
Alektorophobia - Fear of chickens.
Algophobia - Fear of pain.
Alliumphobia - Fear of garlic.
Allodoxaphobia - Fear of opinions.
Altophobia - Fear of heights.
Amathophobia - Fear of dust.
Amaxophobia - Fear of riding in a car.
Ambulophobia - Fear of walking.
Amnesiphobia - Fear of amnesia.
Amychophobia - Fear of scratches or being scratched.
Anablephobia - Fear of looking up.
Ancraophobia - Fear of wind.
Androphobia - Fear of men.
Anemophobia - Fear of air drafts or wind.
Anemophobia - Fear of wind.
Anginophobia - Fear of angina, choking of narrowness.
Anglophobia - Fear of England, English culture, ect.
Angrophobia - Fear of becoming angry.
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Ankylophobia - Fear of immobility of a joint.
Anthophobia - Fear of flowers.
Anthrophobia - Fear of flowers.
Anthropophobia - Fear of people of society.
Antlophobia - Fear of floods.
Anuptaphobia - Fear of staying single.
Apeirophobia - Fear of infinity.
Aphenphosmphobia - Fear of being touched.
Apiphobia - Fear of bees.
Apotemnophobia - Fear of persons with amputations.
Arachibutyrophobia - Fear of peanut butter sticking to the roof of the mouth.
Arachnephobiba - Fear of spiders.
Arachnophobia - Fear of spiders.
Arithmophobia - Fear of numbers.
Arrhenophobia - Fear of men.
Arsonphobia - Fear of fire.
Ashenophobia - Fear of fainting or weakness.
Astraphobia - Fear of thunder and lightning.
Astrapophobia - Fear of thunder and lightning.
Astrophobia - Fear of stars and celestial space.
Asymmetriphobia - Fear of asymmetrical things.
Ataxiophobia - Fear of ataxia (muscular incoordination)
Ataxophobia - Fear of disorder or untidiness.
Atelophobia - Fear of imperfection.
Atephobia - Fear of ruin or ruins.
Athazagoraphobia - Fear of being forgotten or ignored or forgetting.
Atomosophobia - Fear of atomic explosions.
Atychiphobia - Fear of failure.
Aulophobia - Fear of flutes.
Aurophobia - Fear of gold.
Auroraphobia - Fear of Northern Lights.
Autodysomophobia - Fear that one has a vile odor.
Automatonophobia - Fear of ventriloquist's dummies, animatronic creatures, wax statues-anything that falsely represents a sentient being.
Automysophobia - Fear of being dirty.
Autophobia - Fear of being alone or of oneself.
Aviatophobia - Fear of flying.
Aviophobia - Fear of flying.
List of phobias and their meanings: B
List of phobias and their meanings
Bacillophobia - Fear of microbes
Bacteriophobia - Fear of bacteria.
Balenephobia - Fear of pins and needles.
Ballistophobia - Fear of missles or bullets.
Barophobia - Fear of gravity.
Basiphobia - Inability to stand. Fear of walking or falling.
Basophobia - Inability to stand. Fear of walking or falling.
Bathophobia - Fear of depth.
Batonophobia - Fear of plants.
Batophobia - Fear of heights or being close to high buildings.
Batrachophobia - Fear of amphibians, such as frogs, newts, salamanders, etc.
Bibliophobia - Fear of books.
Blennophobia - Fear of slime.
Bogyphobia - Fear of bogies or the bogeyman.
Bolshephobia - Fear of Bulsheviks.
Bromidrophobia - Fear of body smells.
Bromidrosiphobia - Fear of body smells.
Brontophobia - Fear of thunder and lightning.
Bufonophobia - Fear of toads.
List of phobias and their meanings: C
List of phobias and their meanings
Cacophobia - Fear of ugliness.
Cainophobia - Fear of newness, novelty.
Cainotophobia - Fear of newness, novelty.
Caligynephobia - Fear of beautiful women.
Cancerophobia - Fear of cancer.
Carcinophobia - Fear of cancer.
Cardiophobia - Fear of the heart.
Carnophobia - Fear of meat.
Catagelophobia - Fear of being ridiculed.
Catapedaphobia - Fear of jumping from high and low places.
Cathisophobia - Fear of sitting.
Catoptrophobia - Fear of mirrors.
Cenophobia - Fear of new things or ideas.
Centophobia - Fear of new things or ideas.
Ceraunophobia - Fear of thunder.
Chaetophobia - Fear of hair.
Cheimaphobia - Fear of cold.
Cheimatophobia - Fear of cold.
chemophobia - Fear of chemicals or working with chemicals.
Cherophobia - Fear of gaiety.
Chionophobia - Fear of snow.
Chiraptophobia - Fear of being touched.
Cholerophobia - Fear of anger or the fear of cholera.
Chorophobia - Fear of dancing.
Chrematophobia - Fear of money.
Chromatophobia - Fear of colors.
Chrometophobia - Fear of money.
Chromophobia - Fear of colors.
Chronomentrophobia - Fear of clocks.
Chronophobia - Fear of time.
Cibophobia - Fear of food.
Claustrophobia - Fear of confined spaces.
Cleisiophobia - Fear of being locked in an enclosed place.
Cleithrophobia - Fear of being enclosed.,br>Cleithrophobia - Fear of being locked in an enclosed place.,br>Cleptophobia - Fear of stealing.
Climacophobia - Fear of stairs, climbing or of falling downstairs.
Clinophobia - Fear of going to bed.
Clithrophobia - Fear of being enclosed.
Cnidophobia - Fear of strings.
Coimetrophobia - Fear of cemeteries.
Coitophobia - Fear of coitus.
Cometophobia - Fear of comets.
Contreltophobia - Fear of sexual abuse.
Coprastasophobia - Fear of constipation.
Coprophobia - Fear of feces.
Coulrophobia - Fear of clowns.
Counterphobia - The preference by a phobic for fearful situations.
Cremnophobia - Fear of precipices.
Cryophobia - Fear fo extreme cold, ice or frost.
Crystallophobia - Fear of crystals or glass.
Cyberphobia - Fear of computers or working on a computer.
Cyclophobia - Fear of bicycles.
Cymophobia - Fear of waves or wave like motions.
Cynophobia - Fear of dogs or rabies.
Cyprianophobia - Fear of prostitutes or venereal disease.
Cypridophobia - Fear of prostitutes or venereal disease.
Cyprinophobia - Fear of prostitutes or venereal disease.
Cypriphobia - Fear of prostitutes or venereal disease.
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The List of phobias and their meanings: D
List of phobias and their meanings
Daemonophobia - Fear of demons.
Decidophobia - Fear of making decisions.
Defecaloesiphobia - Fear of painful bowels movements.
Deipnophobia - Fear of dining and dinner conversation.
Dematophobia - Fear of skin lesions.
Dementophobia - Fear of insanity.
Demonophobia - Fear of demons.
Demophobia - Fear of crowds.
Dendrophobia - Fear of trees.
Dentophobia - Fear of dentist.
Dermatophathophobia - Fear of skin disease.
Dermatophobia - Fear of skin disease.
Dermatosiophobia - Fear of skin disease.
Dextrophobia - Fear of objects at the right side of the body.
Diabetophobia - Fear of diabetes.
Didaskaleinophobia - Fear of going to school.
Diderodromophobia - Fear of trains, railroads or train travel.
Dikephobia - Fear of justice.
Dinophobia - Fear of dizziness or whirlpools.
Diplophobia - Fear of double vision.
Dipsophobia - Fear drinking.
Dishabiliophobia - Fear of undressing in front of someone.
Domatophobia - Fear of houses or being in a home.
Doraphobia - Fear of fur or skins of animals
.Dromophobia - Fear of crossing streets.
Dutchphobia - Fear of the Dutch.
Dysmorphophobia - Fear of deformity.
Dystychiphobia - Fear of accidents.
List of phobias and their meanings: E
List of phobias and their meanings
Ecclesiophobia - Fear of church.
Ecophobia - Fear of home.
Eicophobia - Fear of home surroundings.
Eisoptrophobia - Fear of mirrors or of seeing oneself in a mirror.
Electrophobia - Fear of electricity.
Eleutherophobia - Fear of freedom.
Elurophobia - Fear of cats.
Emetophobia - Fear of vomiting.
Enetophobia - Fear of pins.
Enissophobia - Fear of having committed an unpardonable sin or of criticism.
Enochlophobia - Fear of crowds.
Enosiophobia - Fear of having committed an unpardonable sin or of criticism.
Entomophobia - Fear of insects.
Eosophobia - Fear of dawn or daylight.
Epistaxiophobia - Fear of nosebleeds.
Epistemphobia - Fear of knowledge.
Equinophobia - Fear of hourse.
Eremophobia - Fear of being oneself or of lonliness.
Ereuthophobia - Fear of redlights. Fear of blushing. Fear of red.
Ereuthrophobia - Fear of blushing.
Ergasiophobia - Fear of work or functioning. Surgeon's fear of operating.
Ergophobia - Fear of work.
Erotophobia - Fear of sexual love or sexual questions.
Erythrophobia - Fear of redlights. Fear of blushing. Fear of red.
Erytophobia- Fear of redlights. Fear of blushing. Fear of red.
Euphobia - Fear of hearing good news.
Eurotophobia - Fear of female genitalia.
List of phobias and their meanings: F
List of phobias and their meanings
Febriphobia - Fear of fever.
Felinophobia - Fear of cats.
Fibriophobia - Fear of fever.
Fibriphobia - Fear of fever.
Francophobia - Fear of France, French culture.
List of phobias and their meanings: G
List of phobias and their meanings
Galeophobia - Fear of cats.
Galiophobia - Fear of France, French culture.
Gallophobia - Fear of France, French culture.
Gamophobia - Fear of marriage.
Gatophobia - Fear of cats.
Geliophobia - Fear of laughter.
Geniophobia - Fear of chins.
Genophobia - Fear of sex.
Genuphobia - Fear of knees.
Gephydrophobia - Fear of crossing bridges.
Gephyrophobia - Fear of crossing bridges.
Gephysrophobia - Fear of crossing bridges.
Gerascophobia - Fear of growing old.
Germanophobia - Fear of Germany, German culture, etc.
Gerontophobia - Fear of old people or of growing old.
Geumaphobia - Fear of taste.
Geumophobia - Fear of taste.Gnosiophobia - Fear of knowledge.
Graphophobia - Fear of writing or handwritting.
Gymnophobia - Fear of nudity.
Gynephobia - Fear of women.
Gynophobia - Fear of women.
List of phobias and their meanings: H
List of phobias and their meanings
Hadephobia - Fear of hell.
Hagiophobia - Fear of saints or holy things.
Hamartophobia - Fear of sinning.
Haphephobia - Fear of being touched.
Haptephobia - Fear of being touched.
Harpaxophobia - Fear of being robbed.
Hedonophobia - Fear of feeling pleasure.
Heliophobia - Fear of the sun.
Hellenologophobia - Fear of Greek terms or complex scientific terminology.
Helminthophobia - Fear of being infested with worms.
Hemaphobia - Fear of blood.
Hematophobia - Fear of blood.
Hemophobia - Fear of blood.
Hereiophobia - Fear of challenges to official doctrine or of radical deviation.
Heresyphobia - Fear of challenges to official doctrine or radical deviation.
Herpetophobia - Fear of reptiles or creepy, crawly things.
Heterophobia - Fear of the opposite sex.
Hierophobia - Fear of priest or sacred things.
Hippophobia - Fear of horses.
Hippopotomonstrosesquippedaliophobia - Fear of long words.
Hobophobia - Fear of bums or beggars.
Hodophobia - Fear of road travel.
Homichlophobia - Fear of fog.
Homilophobia - Fear of sermons.
Hominophobia - Fear of men.
Homophobia - Fear of sameness, monotony or of homosexuality or of becoming homosexual.
Hoplophobia * Fear of firearms.
Hormephobia - Fear of shock.
Hydrargyophobia - Fear of mercuial medicines.
Hydrophobia - Fear of water of of rabies.
Hydrophobophobia - Fear or rabies.
Hyelophobia - Fear of glass.
Hygrophobia - Fear of liquids, dampness, or moisture.
Hylephobia - Fear of materialism or the fear of epilepsy.
Hylophobia - Fear of forests.
Hynophobia - Fear of sleep or of being hypnotized.
Hypegiaphobia - Fear of responsibility.
Hypengyophobia - Fear of responsibility.
Hypsiphobia - Fear of height.
List of phobias and their meanings: I
List of phobias and their meanings
Iatrophobia - Fear of going to the doctor or doctors.
Ichthyophobia - Fear of fish.
Ideophobia - Fear of ideas.
Illyngophobia - Fear of vertigo or feeling dizzy when looking down.
insectophobia - fear of insects.
Iophobia - Fear of poison.
Isolophobia - Fear of solitude, being alone.
Isopterophobia - Fear of termites, insects that eat wood.
Ithyphallophobia - Fear of seeing, thinking about, or having an erect penis.
The List of phobias and their meanings: J
List of phobias and their meanings
Japanophobia - Fear of Japanese.
Judeophobia - Fear of Jews.
The List of phobias and their meanings: K
List of phobias and their meanings
Kainolophobia - Fear of novelty.
Kainophobia - Fear of anything new, novelty.
Kakorrhaphiophobia - Fear of failure or defeat.
Katagelophobia - Fear of ridicule.
Kathisophobia - Fear of sitting down.
Kenophobia - Fear of voids or empty spaces.
Keraunophobia - Fear of thunder and lightning.
Kinesophobia - Fear of movement or motion.
Kinetophobia - Fear of movement or motion.
Kleptophobia - Fear of movement or motion.
Koinoniphobia - Fear of rooms.
Kolpophobia - Fear of genitals, particulary female.
Koniophobia - Fear of dust.
Kopophobia - Fear of fatigue.
Kosmikophobi - Fear of cosmic phenomenon.
Kymophobia - Fear of waves.
Kynophobia - Fear of rabies.
Kyphophobia - Fear of stooping.
List of phobias and their meanings: L
List of phobias and their meanings
Lachanophobia - Fear of vegitables.
Laliophobia - Fear of speaking.
Lalophobia - Fear of speaking.
Lepraphobia - Fear of leprosy.
Leprophobia - Fear of leprosy.
Leukophobia - Fear of the color white.
Levophobia - Fear of things to the left side of the body.
Ligyrophobia - Fear of loud noises.
Lilapsophobia - Fear of tornadoes and hurricanes.
Limnophobia - Fear of lakes.
Linonophobia - Fear of string.
Liticaphobia - Fear of lawsuits.
Lockiophobia - Fear fo childbirth.
Logizomechanophobia - Fear of computers.
Logophobia - Fear of words.
Luiphobia - Fear of lues, syphillis.
Lutraphobia - Fear of otters.
Lygophobia - Fear of darkness.
Lysssophobia - Fear of rabies or of becoming mad.
The List of phobias and their meanings: M
List of phobias and their meanings
Macrophobia - Fear of long waits.
Mageirocophobia *- Fear of cooking.
Maieusiophobia - Fear of childbirth.
Malaxophobia - Fear of love play.
Maniaphobia - Fear of insanity.
Mastigophobia - Fear of punishment.
Mechanophobia - Fear of machines.
Medomalacuphobia - Fear of losing an erection.
Medorthophobia - Fear of an erect penis.
Megalophobia - Fear of large things.
Melanophobia - Fear of the color black.
Melissophobia - Fear of bees.
Melophobia - Fear of hatred or music.
Meningitiophobia - Fear of brain disease.
Merinthophobia - Fear of being bound or tied up.
Mertophobia - Fear or hatred of poetry.
Metallophobia - Fear of metal.
Metathesiophobia - Fear of changes.
Meterorophobia - Fear of Meteors.
Methyphobia - Fear of alcohol.
Microbiophobia - Fear of microbes.
Microphobia - Fear of small things.
Misophobia - Fear of being contaminated with dirt or germs.
Mnemophobia - Fear of memories.
Molysmophobia - Fear of dirt or contamination.
Molysomophobia - Fear of dirt or contamination.
Monopathophobia - Fear of difinite disease.
Monophobia - Fear of solitude or being alone.
Monophobia - Fear of menstruation.
Motorphobia - Fear of automobiles.
Mottophobia - Fear of moths.
Murophobia - Fear of mice.
Musophobia - Fear of mice.
Mycophobia - Fear or aversion to mushrooms.
Mycrophobia - Fear of small things.
Myctophobia - Fear of darkness.
Myrmecophobia - Fear of ants.
Mysophobia - Fear of germs or contamination or dirt.
Mythophobia - Fear of myths or stories or false statements.
Myxophobia - Fear of slime.
The List of phobias and their meanings: N
List of phobias and their meanings
Namatophobia - Fear of names.
Nebulaphobia - Fear of fog.
Necrophobia - Fear of death or or dead things.
Nelophobia - Fear of glass.
Neopharmaphobia - Fear of new drugs.
neophobia - Fear of anything new.
Nephophobia - Fear of clouds.
Noctiphobia - Fear of the night.
Nosemaphobia - Fear of becoming ill.
Nosocomephobia - Fear of hospitals.
Nosophobia - Fear of becoming ill.
Nostophobia - Fear of returning home.
Novercaphobia - Fear of your step-mother.
Nucleomituphobia - Fear of nuclear weapons.
Nudophobia - Fear of nudity.
Numerophobia - Fear of numbers.
Nyctohlophobia - Fear of dark wooded areas, of forest at night.
Nyctophobia - Fear of the dark or of the night.
The List of phobias and their meanings: O
List of phobias and their meanings
Obesophobia - Fear of gaining weight.
Ochlophobia - Fear of crowds or mobs.
Ochophobia - Fear of vehicles.
Octophobia - Fear of the figure 8.
Odontophobia - Fear of teeth or dental surgery.
Odynephobia - Fear of pain.
Odynophobia - Fear of pain.
Oenophobia - Fear of wines.
Oikophobia - Fear of home surroundings, house.
Oikophobia - Fear of houses or being in a house.
Oikophobia - Fear of home surroundings.
Olfactophobia - Fear of smells.
Ombrophobia - Fear of rain or being rained on.
Ommatophobia - Fear of eyes.
Ommetaphobia - Fear of eyes.
Oneirogmophobia - Fear of wet dreams.
Oneirophobia - Fear of dreams.
Onomatophobia - Fear of hearing a certain word or names.
Ophidiophobia - Fear of snakes.
Opthalmophobia - Fear of being stared at.
Optophobia - Fear of opening one's eyes.
Ornithophobia - Fear of birds.
Orthophobia - Fear of property.
Osmophobia - Fear of smells or odors.
Osphesiophobia - Fear of smells or odors.
Ostraconophobia - Fear of shellfish.
Ouranophobia - Fear of heaven.
The List of phobias and their meanings: P
List of phobias and their meanings
Pagophobia - Fear of ice or frost.
Panophobia - Fear of everything.
Panthophobia - Fear of suffering and disease.
Pantophobia - Fear of everything.
Papaphobia - Fear fo the Pope.
Papyrophobia - Fear of paper.
Paralipophobia - Fear of neglecting duty or responsibility.
Paraphobia - Fear of sexual perversion.
Parasitophobia - Fear of parasites.
Paraskavedekatriaphobia - Fear of Friday the 13th.
Parthenophobia - Fear of virgins or young girls.
Parturiphobia - Fear of childbirth.
Pathophobia - Fear of disease.
Patroiophobia - Fear of heredity.
Peccatophobia - Fear of sinning. (imaginary crime)
Pediculophobia - Fear of lice.
Pediophobia - Fear of dolls.
Pedophobia - Fear of children.
Peladophobia - Fear of bald people.
Pellagrophobia - Fear of pellagra.
Peniaphobioa - Fear of poverty.
Pentheraphobia - Fear of mother-in-law.
Phagophobia - Fear of swallowing or eating or of being eaten.
Phalacrophobia - Fear of becoming bald.
Phallophobia - Fear of penis, esp erect.
Pharmacophobia - Fear of taking medicine.
Pharmacophobia - Fear of drugs.
Phasmophobia - Fear of ghost.
Phengophobia - Fear of daylight or sunshine.
Philemaphobia - Fear of kissing.
Philematophobia - Fear of kissing.
Philophobia - Fear of falling in love or being in love.
Philosophobia - Fear of philosophy.
Phobophobia - Fear of phobias.
Phonophobia - Fear of noises or voices or one's own voice; of telephones.
Photoaugliaphobia - Fear of glaring lights.
Photophobia - Fear of light.
Phronemophobia - Fear of thinking.
Phthiriophobia - Fear of lice.
Phthisiophobia - Fear of tuberculosis.
Placophobia - Fear of tombstones.
Plutophobia - Fear of wealth.
Pluviophobia - Fear of rain or of being rained on.
Pneumatiphobia - Fear of spirits.
Pnigerophobia - Fear of choking or of being smothered.
Pnigophobia - Fear of choking or of being smothered.
Pocrescophobia - Fear of gaining weight.
Pocresophobia - Fear of gaining weight.
Pogonophobia - Fear of beards.
Poinephobia - Fear of punishment.
Poliosophobia - Fear of contracting poliomyelitis.
Politicophobia - Fear or abnormal dislike of politicians.
Polyphobia - Fear of many things.
Ponophobia - Fear of overworking or of pain.
Porphyrophobia - Fear of the color purple.
Potamophobia - Fear of rivers or running water.
Potophobia - Fear of alcohol.
Proctophobia - Fear or rectum.
Prosophobia - Fear of progress.
Psellismophobia - Fear of stuttering.
Psychophobia - Fear of mind.
Psychrophobia - Fear of cold.
Pteromerhanophobia - Fear of flying.
Pteronophobia - Fear of being tickled by feathers.
Pupaphobia - Fear of puppets.
Pyrexiophobia - Fear of fever.
Pyrophobia - Fear of fire.
List of phobias and their meanings: Q
List of phobias and their meanings
The A - List of phobias and their meanings: R
List of phobias and their meanings
Radiophobia - Fear of radiation, x-rays.
Ranidaphobia - Fear of frogs.
Rectophobia - Fear of rectum or rectal diseases.
Rhabdophobia - Fear of being severely punished or beaten by a rod, or of being severely criticized. Also fear of magic. (wand)
Rhypophobia - Fear of defecation.
Rhytiphobia - Fear of getting wrinkles.
Rupophobia - Fear of dirt.
Russophobia - Fear of Russians.
List of phobias and their meanings: S
List of phobias and their meanings
Samhainophobia - Fear of Halloween.
Sarmassophobia - Fear of love play.
Sarmassophobia - Fear of love play.
Satanophobia - Fear of Satin.
Scabiophobia - Fear of scabies.
Scatophobia - Fear of fecal matter.
Scelerophobia - Fear of bad men, burglars.
Sciaphobia - Fear of shadows.
Sciophobia - Fear of shadows.
Scoionophobia - Fear of school.
Scoleciphobia - Fear of worms.
Scopophobia - Fear of being seen or stared at.
Scoptophobia - Fear of being seen or stared at.
Scotomaphobia - Fear of blindness in visual field.
Scotophobia - Fear of darkness.
Scriptophobia - Fear of writing in public.
Selaphobia - Fear of light flashes.
Selenophobia - Fear of the moon.
Seplophobia - Fear of decaying matter.
Sesquipedalophobia - Fear of long words.
Sexophobia - Fear of the opposit sex.
Sexophobia - Fear of the opposite sex.
Siderophobia - Fear of stars.
Sinistrophobia - Fear of things to the left, left-handed.
Sinophobia - Fear of Chinese, Chinese culture.
Sitiophobia - Fear of food.
Sitiophobia - Fear of food or eating.
Sitophobia - Fear of food or eating.
Sitophobia - Fear of food.
Snakephobia - Fear of snakes.
Soceraphobia - Fear of parents-in-law.
Social Phobia - Fear of being evaluated negatively in social situations.
Sociophobia - Fear of society or people in general.
Somniphobia - Fear of sleep.
Sophophobia - Fear of learning.
Soteriophobia - Fear of dependence on others.
Spacephobia - Fear of outer space.
Spectrophobia - Fear of specters or ghosts.
Spermatophobia - Fear of germs.
Spermophobia - Fear of germs.
Spheksophobia - Fear of wasps.
Stasibasiphobia - Fear fo standing or walking.
Stasiphobia - Fear of standing or walking.
Staurophobia - Fear of crosses or the crucifix.
Stenophobia - Fear of narrow things or places.
Stigiophobia - Fear of hell.
Stygiophobia - Fear of hell.
Suriphobia - Fear of mice.
Symbolophobia - Fear of symbolism.
Symmetrophobia - Fear of symmetry.
Syngenesophobia - Fear of relatives.
Syphilophobia - Fear of syphilis.
List of phobias and their meanings: T
List of phobias and their meanings
Tachophobia - Fear of speed.
Taeniophobia - Fear of tapeworms.
Teniophobia - Fear of tapeworms.
Taphephobia - Fear of being buried alive or of cemeteries.
Taphophobia - Fear of being buried alive or of cemeteries.
Tapinophobia - Fear of being contagious.
Taurophobia - Fear of bulls.
Technophobia - Fear of technology.
Teleophobia - Fear fo difinite plans. Fear of Religious ceremony.
Telephonophobia - Fear of telephones.
Teratophobia - Fear of bearing a deformed child or fear of monsters or deformed people.
Testaphobia - Fear of taking test.
Tetanophobia - Fear of lockjaw, tetnus.
Teutophobia - Fear of German or German things.
Textophobia - Fear of certain fabrics.
Thaasophobia - Fear of sitting.
Thalassophobia - Fear of the sea.
Thanatophobia - Fear of death or dying.
Thantophobia - Fear of death or dying.
Theatrophobia - Fear of theaters.
Theophobia - Fear of gods or religion.
Theologicophobia - Fear of theology.
Thermophobia - Fear of heat.
Tocophobia Fear of pregnancy or childbirth.
Tomophobia - Fear of surgical operations.
Tonitrophobia - Fear of thunder.
Topophobia - Fear of certain places or situations, such as stage fright.
Toxiphobia - Fear of poison or of being accidently poisoned.
Toxophobia - Fear of poison or of being accidently poisoned.
Toxicophobia - Fear of poison or of being accidently poisoned.
Traumatophobia - Fear of injury.
Tremophobia - Fear of trembling.
Trichinophobia - Fear of trichinosis.
Trichopathophobia - Fear of hair.
Trichophobia - Fear of hair.
Hypertrichophobia - Fear of hair.
Triskaidekaphobia - Fear of the number 13.
Tropophobia - Fear of moving or making changes.
Trypanophobia - Fear of injections.
Tuberculophobia - Fear of tuberculosis.
Tyrannophobia - Fear of tyrants.
The List of phobias and their meanings: U
List of phobias and their meanings
Uranophobia - Fear of heaven.
Urophobia - Fear of urine or urinating.
The List of phobias and their meanings: U
List of phobias and their meanings
Vaccinophobia - Fear of vaccination.
Venustraphobia - Fear of beautiful women.
Verbophobia - Fear of words.
Verminophobia - Fear of germs.
Vestiphobia - Fear of clothing.
Virginitiphobia - Fear of rape.
Vitricophobia - Fear of step-father.
List of phobias and their meanings: W
List of phobias and their meanings
Walloonphobia - Fear of Walloons.
Wiccaphobia - Fear of witches and witchcraft.
List of phobias and their meanings: X
List of phobias and their meanings
Xanthophobia - Fear of the color yellow or the word yellow.
Xenophobia - Fear of strangers or foreigners.
Xerophobia - Fear of dryness.
Xylophobia - Fear of wooden objects. Forests.
List of phobias and their meanings: Y
List of phobias and their meanings
List of phobias and their meanings: Z
List of phobias and their meanings
Zelophobia - Fear of jelousy.
Zeusophobia - Fear of God or gods.
Zemmiphobia - Fear of the great mole rat.
Zoophobia - Fear of animals.
Ablutophobia - Fear of washing or bathing.
Acarophobia - Fear of itching or of the insects that cause itching.
Acerophobia - Fear of sourness.
Achluophobia - Fear of darkness.
Acousticophobia - Fear of noise.
Aeroacrophobia - Fear of open high places.
Aeronausiphobia - Fear of vomiting secondary to airsickness.
Aerophobia - Fear of drafts, air swallowing, or airborne noxious substances.
Agliophobia - Fear of pain.
Agoraphobia - Fear of open spaces or of being in crowded, public places like markets. Fear of leaving a safe place. Fear of crowds.
Agraphobia - Fear of sexual abuse.
Agrizoophobia - Fear of wild animals.
Agyrophobia - Fear of streets or crossing the street.
Aichmophobia - Fear of needles or pointed objects.
Ailurophobia - Fear of cats.
Albuminurophobia - Fear of kidney disease.
Alektorophobia - Fear of chickens.
Algophobia - Fear of pain.
Alliumphobia - Fear of garlic.
Allodoxaphobia - Fear of opinions.
Altophobia - Fear of heights.
Amathophobia - Fear of dust.
Amaxophobia - Fear of riding in a car.
Ambulophobia - Fear of walking.
Amnesiphobia - Fear of amnesia.
Amychophobia - Fear of scratches or being scratched.
Anablephobia - Fear of looking up.
Ancraophobia - Fear of wind.
Androphobia - Fear of men.
Anemophobia - Fear of air drafts or wind.
Anemophobia - Fear of wind.
Anginophobia - Fear of angina, choking of narrowness.
Anglophobia - Fear of England, English culture, ect.
Angrophobia - Fear of becoming angry.
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Ankylophobia - Fear of immobility of a joint.
Anthophobia - Fear of flowers.
Anthrophobia - Fear of flowers.
Anthropophobia - Fear of people of society.
Antlophobia - Fear of floods.
Anuptaphobia - Fear of staying single.
Apeirophobia - Fear of infinity.
Aphenphosmphobia - Fear of being touched.
Apiphobia - Fear of bees.
Apotemnophobia - Fear of persons with amputations.
Arachibutyrophobia - Fear of peanut butter sticking to the roof of the mouth.
Arachnephobiba - Fear of spiders.
Arachnophobia - Fear of spiders.
Arithmophobia - Fear of numbers.
Arrhenophobia - Fear of men.
Arsonphobia - Fear of fire.
Ashenophobia - Fear of fainting or weakness.
Astraphobia - Fear of thunder and lightning.
Astrapophobia - Fear of thunder and lightning.
Astrophobia - Fear of stars and celestial space.
Asymmetriphobia - Fear of asymmetrical things.
Ataxiophobia - Fear of ataxia (muscular incoordination)
Ataxophobia - Fear of disorder or untidiness.
Atelophobia - Fear of imperfection.
Atephobia - Fear of ruin or ruins.
Athazagoraphobia - Fear of being forgotten or ignored or forgetting.
Atomosophobia - Fear of atomic explosions.
Atychiphobia - Fear of failure.
Aulophobia - Fear of flutes.
Aurophobia - Fear of gold.
Auroraphobia - Fear of Northern Lights.
Autodysomophobia - Fear that one has a vile odor.
Automatonophobia - Fear of ventriloquist's dummies, animatronic creatures, wax statues-anything that falsely represents a sentient being.
Automysophobia - Fear of being dirty.
Autophobia - Fear of being alone or of oneself.
Aviatophobia - Fear of flying.
Aviophobia - Fear of flying.
List of phobias and their meanings: B
List of phobias and their meanings
Bacillophobia - Fear of microbes
Bacteriophobia - Fear of bacteria.
Balenephobia - Fear of pins and needles.
Ballistophobia - Fear of missles or bullets.
Barophobia - Fear of gravity.
Basiphobia - Inability to stand. Fear of walking or falling.
Basophobia - Inability to stand. Fear of walking or falling.
Bathophobia - Fear of depth.
Batonophobia - Fear of plants.
Batophobia - Fear of heights or being close to high buildings.
Batrachophobia - Fear of amphibians, such as frogs, newts, salamanders, etc.
Bibliophobia - Fear of books.
Blennophobia - Fear of slime.
Bogyphobia - Fear of bogies or the bogeyman.
Bolshephobia - Fear of Bulsheviks.
Bromidrophobia - Fear of body smells.
Bromidrosiphobia - Fear of body smells.
Brontophobia - Fear of thunder and lightning.
Bufonophobia - Fear of toads.
List of phobias and their meanings: C
List of phobias and their meanings
Cacophobia - Fear of ugliness.
Cainophobia - Fear of newness, novelty.
Cainotophobia - Fear of newness, novelty.
Caligynephobia - Fear of beautiful women.
Cancerophobia - Fear of cancer.
Carcinophobia - Fear of cancer.
Cardiophobia - Fear of the heart.
Carnophobia - Fear of meat.
Catagelophobia - Fear of being ridiculed.
Catapedaphobia - Fear of jumping from high and low places.
Cathisophobia - Fear of sitting.
Catoptrophobia - Fear of mirrors.
Cenophobia - Fear of new things or ideas.
Centophobia - Fear of new things or ideas.
Ceraunophobia - Fear of thunder.
Chaetophobia - Fear of hair.
Cheimaphobia - Fear of cold.
Cheimatophobia - Fear of cold.
chemophobia - Fear of chemicals or working with chemicals.
Cherophobia - Fear of gaiety.
Chionophobia - Fear of snow.
Chiraptophobia - Fear of being touched.
Cholerophobia - Fear of anger or the fear of cholera.
Chorophobia - Fear of dancing.
Chrematophobia - Fear of money.
Chromatophobia - Fear of colors.
Chrometophobia - Fear of money.
Chromophobia - Fear of colors.
Chronomentrophobia - Fear of clocks.
Chronophobia - Fear of time.
Cibophobia - Fear of food.
Claustrophobia - Fear of confined spaces.
Cleisiophobia - Fear of being locked in an enclosed place.
Cleithrophobia - Fear of being enclosed.,br>Cleithrophobia - Fear of being locked in an enclosed place.,br>Cleptophobia - Fear of stealing.
Climacophobia - Fear of stairs, climbing or of falling downstairs.
Clinophobia - Fear of going to bed.
Clithrophobia - Fear of being enclosed.
Cnidophobia - Fear of strings.
Coimetrophobia - Fear of cemeteries.
Coitophobia - Fear of coitus.
Cometophobia - Fear of comets.
Contreltophobia - Fear of sexual abuse.
Coprastasophobia - Fear of constipation.
Coprophobia - Fear of feces.
Coulrophobia - Fear of clowns.
Counterphobia - The preference by a phobic for fearful situations.
Cremnophobia - Fear of precipices.
Cryophobia - Fear fo extreme cold, ice or frost.
Crystallophobia - Fear of crystals or glass.
Cyberphobia - Fear of computers or working on a computer.
Cyclophobia - Fear of bicycles.
Cymophobia - Fear of waves or wave like motions.
Cynophobia - Fear of dogs or rabies.
Cyprianophobia - Fear of prostitutes or venereal disease.
Cypridophobia - Fear of prostitutes or venereal disease.
Cyprinophobia - Fear of prostitutes or venereal disease.
Cypriphobia - Fear of prostitutes or venereal disease.
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The List of phobias and their meanings: D
List of phobias and their meanings
Daemonophobia - Fear of demons.
Decidophobia - Fear of making decisions.
Defecaloesiphobia - Fear of painful bowels movements.
Deipnophobia - Fear of dining and dinner conversation.
Dematophobia - Fear of skin lesions.
Dementophobia - Fear of insanity.
Demonophobia - Fear of demons.
Demophobia - Fear of crowds.
Dendrophobia - Fear of trees.
Dentophobia - Fear of dentist.
Dermatophathophobia - Fear of skin disease.
Dermatophobia - Fear of skin disease.
Dermatosiophobia - Fear of skin disease.
Dextrophobia - Fear of objects at the right side of the body.
Diabetophobia - Fear of diabetes.
Didaskaleinophobia - Fear of going to school.
Diderodromophobia - Fear of trains, railroads or train travel.
Dikephobia - Fear of justice.
Dinophobia - Fear of dizziness or whirlpools.
Diplophobia - Fear of double vision.
Dipsophobia - Fear drinking.
Dishabiliophobia - Fear of undressing in front of someone.
Domatophobia - Fear of houses or being in a home.
Doraphobia - Fear of fur or skins of animals
.Dromophobia - Fear of crossing streets.
Dutchphobia - Fear of the Dutch.
Dysmorphophobia - Fear of deformity.
Dystychiphobia - Fear of accidents.
List of phobias and their meanings: E
List of phobias and their meanings
Ecclesiophobia - Fear of church.
Ecophobia - Fear of home.
Eicophobia - Fear of home surroundings.
Eisoptrophobia - Fear of mirrors or of seeing oneself in a mirror.
Electrophobia - Fear of electricity.
Eleutherophobia - Fear of freedom.
Elurophobia - Fear of cats.
Emetophobia - Fear of vomiting.
Enetophobia - Fear of pins.
Enissophobia - Fear of having committed an unpardonable sin or of criticism.
Enochlophobia - Fear of crowds.
Enosiophobia - Fear of having committed an unpardonable sin or of criticism.
Entomophobia - Fear of insects.
Eosophobia - Fear of dawn or daylight.
Epistaxiophobia - Fear of nosebleeds.
Epistemphobia - Fear of knowledge.
Equinophobia - Fear of hourse.
Eremophobia - Fear of being oneself or of lonliness.
Ereuthophobia - Fear of redlights. Fear of blushing. Fear of red.
Ereuthrophobia - Fear of blushing.
Ergasiophobia - Fear of work or functioning. Surgeon's fear of operating.
Ergophobia - Fear of work.
Erotophobia - Fear of sexual love or sexual questions.
Erythrophobia - Fear of redlights. Fear of blushing. Fear of red.
Erytophobia- Fear of redlights. Fear of blushing. Fear of red.
Euphobia - Fear of hearing good news.
Eurotophobia - Fear of female genitalia.
List of phobias and their meanings: F
List of phobias and their meanings
Febriphobia - Fear of fever.
Felinophobia - Fear of cats.
Fibriophobia - Fear of fever.
Fibriphobia - Fear of fever.
Francophobia - Fear of France, French culture.
List of phobias and their meanings: G
List of phobias and their meanings
Galeophobia - Fear of cats.
Galiophobia - Fear of France, French culture.
Gallophobia - Fear of France, French culture.
Gamophobia - Fear of marriage.
Gatophobia - Fear of cats.
Geliophobia - Fear of laughter.
Geniophobia - Fear of chins.
Genophobia - Fear of sex.
Genuphobia - Fear of knees.
Gephydrophobia - Fear of crossing bridges.
Gephyrophobia - Fear of crossing bridges.
Gephysrophobia - Fear of crossing bridges.
Gerascophobia - Fear of growing old.
Germanophobia - Fear of Germany, German culture, etc.
Gerontophobia - Fear of old people or of growing old.
Geumaphobia - Fear of taste.
Geumophobia - Fear of taste.Gnosiophobia - Fear of knowledge.
Graphophobia - Fear of writing or handwritting.
Gymnophobia - Fear of nudity.
Gynephobia - Fear of women.
Gynophobia - Fear of women.
List of phobias and their meanings: H
List of phobias and their meanings
Hadephobia - Fear of hell.
Hagiophobia - Fear of saints or holy things.
Hamartophobia - Fear of sinning.
Haphephobia - Fear of being touched.
Haptephobia - Fear of being touched.
Harpaxophobia - Fear of being robbed.
Hedonophobia - Fear of feeling pleasure.
Heliophobia - Fear of the sun.
Hellenologophobia - Fear of Greek terms or complex scientific terminology.
Helminthophobia - Fear of being infested with worms.
Hemaphobia - Fear of blood.
Hematophobia - Fear of blood.
Hemophobia - Fear of blood.
Hereiophobia - Fear of challenges to official doctrine or of radical deviation.
Heresyphobia - Fear of challenges to official doctrine or radical deviation.
Herpetophobia - Fear of reptiles or creepy, crawly things.
Heterophobia - Fear of the opposite sex.
Hierophobia - Fear of priest or sacred things.
Hippophobia - Fear of horses.
Hippopotomonstrosesquippedaliophobia - Fear of long words.
Hobophobia - Fear of bums or beggars.
Hodophobia - Fear of road travel.
Homichlophobia - Fear of fog.
Homilophobia - Fear of sermons.
Hominophobia - Fear of men.
Homophobia - Fear of sameness, monotony or of homosexuality or of becoming homosexual.
Hoplophobia * Fear of firearms.
Hormephobia - Fear of shock.
Hydrargyophobia - Fear of mercuial medicines.
Hydrophobia - Fear of water of of rabies.
Hydrophobophobia - Fear or rabies.
Hyelophobia - Fear of glass.
Hygrophobia - Fear of liquids, dampness, or moisture.
Hylephobia - Fear of materialism or the fear of epilepsy.
Hylophobia - Fear of forests.
Hynophobia - Fear of sleep or of being hypnotized.
Hypegiaphobia - Fear of responsibility.
Hypengyophobia - Fear of responsibility.
Hypsiphobia - Fear of height.
List of phobias and their meanings: I
List of phobias and their meanings
Iatrophobia - Fear of going to the doctor or doctors.
Ichthyophobia - Fear of fish.
Ideophobia - Fear of ideas.
Illyngophobia - Fear of vertigo or feeling dizzy when looking down.
insectophobia - fear of insects.
Iophobia - Fear of poison.
Isolophobia - Fear of solitude, being alone.
Isopterophobia - Fear of termites, insects that eat wood.
Ithyphallophobia - Fear of seeing, thinking about, or having an erect penis.
The List of phobias and their meanings: J
List of phobias and their meanings
Japanophobia - Fear of Japanese.
Judeophobia - Fear of Jews.
The List of phobias and their meanings: K
List of phobias and their meanings
Kainolophobia - Fear of novelty.
Kainophobia - Fear of anything new, novelty.
Kakorrhaphiophobia - Fear of failure or defeat.
Katagelophobia - Fear of ridicule.
Kathisophobia - Fear of sitting down.
Kenophobia - Fear of voids or empty spaces.
Keraunophobia - Fear of thunder and lightning.
Kinesophobia - Fear of movement or motion.
Kinetophobia - Fear of movement or motion.
Kleptophobia - Fear of movement or motion.
Koinoniphobia - Fear of rooms.
Kolpophobia - Fear of genitals, particulary female.
Koniophobia - Fear of dust.
Kopophobia - Fear of fatigue.
Kosmikophobi - Fear of cosmic phenomenon.
Kymophobia - Fear of waves.
Kynophobia - Fear of rabies.
Kyphophobia - Fear of stooping.
List of phobias and their meanings: L
List of phobias and their meanings
Lachanophobia - Fear of vegitables.
Laliophobia - Fear of speaking.
Lalophobia - Fear of speaking.
Lepraphobia - Fear of leprosy.
Leprophobia - Fear of leprosy.
Leukophobia - Fear of the color white.
Levophobia - Fear of things to the left side of the body.
Ligyrophobia - Fear of loud noises.
Lilapsophobia - Fear of tornadoes and hurricanes.
Limnophobia - Fear of lakes.
Linonophobia - Fear of string.
Liticaphobia - Fear of lawsuits.
Lockiophobia - Fear fo childbirth.
Logizomechanophobia - Fear of computers.
Logophobia - Fear of words.
Luiphobia - Fear of lues, syphillis.
Lutraphobia - Fear of otters.
Lygophobia - Fear of darkness.
Lysssophobia - Fear of rabies or of becoming mad.
The List of phobias and their meanings: M
List of phobias and their meanings
Macrophobia - Fear of long waits.
Mageirocophobia *- Fear of cooking.
Maieusiophobia - Fear of childbirth.
Malaxophobia - Fear of love play.
Maniaphobia - Fear of insanity.
Mastigophobia - Fear of punishment.
Mechanophobia - Fear of machines.
Medomalacuphobia - Fear of losing an erection.
Medorthophobia - Fear of an erect penis.
Megalophobia - Fear of large things.
Melanophobia - Fear of the color black.
Melissophobia - Fear of bees.
Melophobia - Fear of hatred or music.
Meningitiophobia - Fear of brain disease.
Merinthophobia - Fear of being bound or tied up.
Mertophobia - Fear or hatred of poetry.
Metallophobia - Fear of metal.
Metathesiophobia - Fear of changes.
Meterorophobia - Fear of Meteors.
Methyphobia - Fear of alcohol.
Microbiophobia - Fear of microbes.
Microphobia - Fear of small things.
Misophobia - Fear of being contaminated with dirt or germs.
Mnemophobia - Fear of memories.
Molysmophobia - Fear of dirt or contamination.
Molysomophobia - Fear of dirt or contamination.
Monopathophobia - Fear of difinite disease.
Monophobia - Fear of solitude or being alone.
Monophobia - Fear of menstruation.
Motorphobia - Fear of automobiles.
Mottophobia - Fear of moths.
Murophobia - Fear of mice.
Musophobia - Fear of mice.
Mycophobia - Fear or aversion to mushrooms.
Mycrophobia - Fear of small things.
Myctophobia - Fear of darkness.
Myrmecophobia - Fear of ants.
Mysophobia - Fear of germs or contamination or dirt.
Mythophobia - Fear of myths or stories or false statements.
Myxophobia - Fear of slime.
The List of phobias and their meanings: N
List of phobias and their meanings
Namatophobia - Fear of names.
Nebulaphobia - Fear of fog.
Necrophobia - Fear of death or or dead things.
Nelophobia - Fear of glass.
Neopharmaphobia - Fear of new drugs.
neophobia - Fear of anything new.
Nephophobia - Fear of clouds.
Noctiphobia - Fear of the night.
Nosemaphobia - Fear of becoming ill.
Nosocomephobia - Fear of hospitals.
Nosophobia - Fear of becoming ill.
Nostophobia - Fear of returning home.
Novercaphobia - Fear of your step-mother.
Nucleomituphobia - Fear of nuclear weapons.
Nudophobia - Fear of nudity.
Numerophobia - Fear of numbers.
Nyctohlophobia - Fear of dark wooded areas, of forest at night.
Nyctophobia - Fear of the dark or of the night.
The List of phobias and their meanings: O
List of phobias and their meanings
Obesophobia - Fear of gaining weight.
Ochlophobia - Fear of crowds or mobs.
Ochophobia - Fear of vehicles.
Octophobia - Fear of the figure 8.
Odontophobia - Fear of teeth or dental surgery.
Odynephobia - Fear of pain.
Odynophobia - Fear of pain.
Oenophobia - Fear of wines.
Oikophobia - Fear of home surroundings, house.
Oikophobia - Fear of houses or being in a house.
Oikophobia - Fear of home surroundings.
Olfactophobia - Fear of smells.
Ombrophobia - Fear of rain or being rained on.
Ommatophobia - Fear of eyes.
Ommetaphobia - Fear of eyes.
Oneirogmophobia - Fear of wet dreams.
Oneirophobia - Fear of dreams.
Onomatophobia - Fear of hearing a certain word or names.
Ophidiophobia - Fear of snakes.
Opthalmophobia - Fear of being stared at.
Optophobia - Fear of opening one's eyes.
Ornithophobia - Fear of birds.
Orthophobia - Fear of property.
Osmophobia - Fear of smells or odors.
Osphesiophobia - Fear of smells or odors.
Ostraconophobia - Fear of shellfish.
Ouranophobia - Fear of heaven.
The List of phobias and their meanings: P
List of phobias and their meanings
Pagophobia - Fear of ice or frost.
Panophobia - Fear of everything.
Panthophobia - Fear of suffering and disease.
Pantophobia - Fear of everything.
Papaphobia - Fear fo the Pope.
Papyrophobia - Fear of paper.
Paralipophobia - Fear of neglecting duty or responsibility.
Paraphobia - Fear of sexual perversion.
Parasitophobia - Fear of parasites.
Paraskavedekatriaphobia - Fear of Friday the 13th.
Parthenophobia - Fear of virgins or young girls.
Parturiphobia - Fear of childbirth.
Pathophobia - Fear of disease.
Patroiophobia - Fear of heredity.
Peccatophobia - Fear of sinning. (imaginary crime)
Pediculophobia - Fear of lice.
Pediophobia - Fear of dolls.
Pedophobia - Fear of children.
Peladophobia - Fear of bald people.
Pellagrophobia - Fear of pellagra.
Peniaphobioa - Fear of poverty.
Pentheraphobia - Fear of mother-in-law.
Phagophobia - Fear of swallowing or eating or of being eaten.
Phalacrophobia - Fear of becoming bald.
Phallophobia - Fear of penis, esp erect.
Pharmacophobia - Fear of taking medicine.
Pharmacophobia - Fear of drugs.
Phasmophobia - Fear of ghost.
Phengophobia - Fear of daylight or sunshine.
Philemaphobia - Fear of kissing.
Philematophobia - Fear of kissing.
Philophobia - Fear of falling in love or being in love.
Philosophobia - Fear of philosophy.
Phobophobia - Fear of phobias.
Phonophobia - Fear of noises or voices or one's own voice; of telephones.
Photoaugliaphobia - Fear of glaring lights.
Photophobia - Fear of light.
Phronemophobia - Fear of thinking.
Phthiriophobia - Fear of lice.
Phthisiophobia - Fear of tuberculosis.
Placophobia - Fear of tombstones.
Plutophobia - Fear of wealth.
Pluviophobia - Fear of rain or of being rained on.
Pneumatiphobia - Fear of spirits.
Pnigerophobia - Fear of choking or of being smothered.
Pnigophobia - Fear of choking or of being smothered.
Pocrescophobia - Fear of gaining weight.
Pocresophobia - Fear of gaining weight.
Pogonophobia - Fear of beards.
Poinephobia - Fear of punishment.
Poliosophobia - Fear of contracting poliomyelitis.
Politicophobia - Fear or abnormal dislike of politicians.
Polyphobia - Fear of many things.
Ponophobia - Fear of overworking or of pain.
Porphyrophobia - Fear of the color purple.
Potamophobia - Fear of rivers or running water.
Potophobia - Fear of alcohol.
Proctophobia - Fear or rectum.
Prosophobia - Fear of progress.
Psellismophobia - Fear of stuttering.
Psychophobia - Fear of mind.
Psychrophobia - Fear of cold.
Pteromerhanophobia - Fear of flying.
Pteronophobia - Fear of being tickled by feathers.
Pupaphobia - Fear of puppets.
Pyrexiophobia - Fear of fever.
Pyrophobia - Fear of fire.
List of phobias and their meanings: Q
List of phobias and their meanings
The A - List of phobias and their meanings: R
List of phobias and their meanings
Radiophobia - Fear of radiation, x-rays.
Ranidaphobia - Fear of frogs.
Rectophobia - Fear of rectum or rectal diseases.
Rhabdophobia - Fear of being severely punished or beaten by a rod, or of being severely criticized. Also fear of magic. (wand)
Rhypophobia - Fear of defecation.
Rhytiphobia - Fear of getting wrinkles.
Rupophobia - Fear of dirt.
Russophobia - Fear of Russians.
List of phobias and their meanings: S
List of phobias and their meanings
Samhainophobia - Fear of Halloween.
Sarmassophobia - Fear of love play.
Sarmassophobia - Fear of love play.
Satanophobia - Fear of Satin.
Scabiophobia - Fear of scabies.
Scatophobia - Fear of fecal matter.
Scelerophobia - Fear of bad men, burglars.
Sciaphobia - Fear of shadows.
Sciophobia - Fear of shadows.
Scoionophobia - Fear of school.
Scoleciphobia - Fear of worms.
Scopophobia - Fear of being seen or stared at.
Scoptophobia - Fear of being seen or stared at.
Scotomaphobia - Fear of blindness in visual field.
Scotophobia - Fear of darkness.
Scriptophobia - Fear of writing in public.
Selaphobia - Fear of light flashes.
Selenophobia - Fear of the moon.
Seplophobia - Fear of decaying matter.
Sesquipedalophobia - Fear of long words.
Sexophobia - Fear of the opposit sex.
Sexophobia - Fear of the opposite sex.
Siderophobia - Fear of stars.
Sinistrophobia - Fear of things to the left, left-handed.
Sinophobia - Fear of Chinese, Chinese culture.
Sitiophobia - Fear of food.
Sitiophobia - Fear of food or eating.
Sitophobia - Fear of food or eating.
Sitophobia - Fear of food.
Snakephobia - Fear of snakes.
Soceraphobia - Fear of parents-in-law.
Social Phobia - Fear of being evaluated negatively in social situations.
Sociophobia - Fear of society or people in general.
Somniphobia - Fear of sleep.
Sophophobia - Fear of learning.
Soteriophobia - Fear of dependence on others.
Spacephobia - Fear of outer space.
Spectrophobia - Fear of specters or ghosts.
Spermatophobia - Fear of germs.
Spermophobia - Fear of germs.
Spheksophobia - Fear of wasps.
Stasibasiphobia - Fear fo standing or walking.
Stasiphobia - Fear of standing or walking.
Staurophobia - Fear of crosses or the crucifix.
Stenophobia - Fear of narrow things or places.
Stigiophobia - Fear of hell.
Stygiophobia - Fear of hell.
Suriphobia - Fear of mice.
Symbolophobia - Fear of symbolism.
Symmetrophobia - Fear of symmetry.
Syngenesophobia - Fear of relatives.
Syphilophobia - Fear of syphilis.
List of phobias and their meanings: T
List of phobias and their meanings
Tachophobia - Fear of speed.
Taeniophobia - Fear of tapeworms.
Teniophobia - Fear of tapeworms.
Taphephobia - Fear of being buried alive or of cemeteries.
Taphophobia - Fear of being buried alive or of cemeteries.
Tapinophobia - Fear of being contagious.
Taurophobia - Fear of bulls.
Technophobia - Fear of technology.
Teleophobia - Fear fo difinite plans. Fear of Religious ceremony.
Telephonophobia - Fear of telephones.
Teratophobia - Fear of bearing a deformed child or fear of monsters or deformed people.
Testaphobia - Fear of taking test.
Tetanophobia - Fear of lockjaw, tetnus.
Teutophobia - Fear of German or German things.
Textophobia - Fear of certain fabrics.
Thaasophobia - Fear of sitting.
Thalassophobia - Fear of the sea.
Thanatophobia - Fear of death or dying.
Thantophobia - Fear of death or dying.
Theatrophobia - Fear of theaters.
Theophobia - Fear of gods or religion.
Theologicophobia - Fear of theology.
Thermophobia - Fear of heat.
Tocophobia Fear of pregnancy or childbirth.
Tomophobia - Fear of surgical operations.
Tonitrophobia - Fear of thunder.
Topophobia - Fear of certain places or situations, such as stage fright.
Toxiphobia - Fear of poison or of being accidently poisoned.
Toxophobia - Fear of poison or of being accidently poisoned.
Toxicophobia - Fear of poison or of being accidently poisoned.
Traumatophobia - Fear of injury.
Tremophobia - Fear of trembling.
Trichinophobia - Fear of trichinosis.
Trichopathophobia - Fear of hair.
Trichophobia - Fear of hair.
Hypertrichophobia - Fear of hair.
Triskaidekaphobia - Fear of the number 13.
Tropophobia - Fear of moving or making changes.
Trypanophobia - Fear of injections.
Tuberculophobia - Fear of tuberculosis.
Tyrannophobia - Fear of tyrants.
The List of phobias and their meanings: U
List of phobias and their meanings
Uranophobia - Fear of heaven.
Urophobia - Fear of urine or urinating.
The List of phobias and their meanings: U
List of phobias and their meanings
Vaccinophobia - Fear of vaccination.
Venustraphobia - Fear of beautiful women.
Verbophobia - Fear of words.
Verminophobia - Fear of germs.
Vestiphobia - Fear of clothing.
Virginitiphobia - Fear of rape.
Vitricophobia - Fear of step-father.
List of phobias and their meanings: W
List of phobias and their meanings
Walloonphobia - Fear of Walloons.
Wiccaphobia - Fear of witches and witchcraft.
List of phobias and their meanings: X
List of phobias and their meanings
Xanthophobia - Fear of the color yellow or the word yellow.
Xenophobia - Fear of strangers or foreigners.
Xerophobia - Fear of dryness.
Xylophobia - Fear of wooden objects. Forests.
List of phobias and their meanings: Y
List of phobias and their meanings
List of phobias and their meanings: Z
List of phobias and their meanings
Zelophobia - Fear of jelousy.
Zeusophobia - Fear of God or gods.
Zemmiphobia - Fear of the great mole rat.
Zoophobia - Fear of animals.
Monday 5 March 2012
Homeostasis
Homeostasis
The human body has the ability to maintain a constant internal environment so that every organ and cell is provided the perfect conditions to perform its functions. This is called homeostasis. There is no organ system for this function. However, every organ plays a role in maintaining a constant internal environment. For example the lungs are responsible for the supply of oxygen to cells. The liver is to maintain a constant level of glucose and amino acids, and so on..
Temperature Regulation:
A healthy human should have a body temperature of 37°C. If the body temperature drops below 37°C, metabolic reactions become slower because molecules move slower and have less kinetic energy. If the temperature rises above 37°C, the enzymes of the body begin to get denatured and metabolic reactions will be much slower.
Sometimes, the temperature of the area you are at is low enough to decrease your body temperature. Sometimes it is high enough to raise your body temperature. This is why the body has the ability to control its body temperature. Our skin is responsible for this process. The Human Skin:
The skin is an organ that coats your entire body. The skin is made up of two layers, the Epidermis and the dermis.
The epidermis’s main function is to protect the dermis which contains most of the structures, and protect the body from ultra-violet rays. The surface of the epidermis is made of tough, dead cells.
The dermis contains many useful structures. Hairs, sweat and sebaceous glands, sense receptors and erector muscles are responsible for controlling the body temperature. Blood vessels transport oxygen and nutrients to the cells of the skin.
A healthy body is continuously gaining and losing heat. Metabolic reactions like respiration release a lot of heat energy, muscular activity increase the metabolic rate and release more heat energy. The body can also gain temperature from the surroundings like the sun or by eating hot food. Heat is lost by the body through exposed skin by conduction. If there is sweat or water on the skin, it will absorb body heat to evaporate which drops the temperature. All these factors are normal however, but it is considered dangerous when the body temperature keeps on dropping or rising severely.
Cooling Down the Body:
When the body is overheated, the body takes several actions to drop it by trying to lose heat in several ways:
Vasodilation: this action causes the body to lose heat quickly. It involves widening the lumen of blood vessels of the skin, this increases blood flow and rate of heat loss. The vessels are also brought near the surface of the skin to reduce the distance heat has to travel to escape.
Sweating: Sweat glands near the skin begin to secret sweat on the surface of the skin through the pores. This sweat acts as a heat consumer to absorb the body heat and use it in evaporation. The activity of sweat glands is increased when the temperature of the body rises.
Hairs lie flat: The muscle erectors of the hairs relax making the hairs lay flat of the skin. When the hairs are erect, they trap air in the gaps between them, this acts as an insulation and prevents heat loss. But when the hairs are flat, less air is trapped between them so there is no insulation and more heat can be lost.
Heating Up the Body:
When the body temperatures drop, the body takes several actions to regulate its temperature by insulation to prevent heat loss and producing heat energy:
Vasoconstriction: this causes the blood vessels to become narrower to reduce heat loss. They also sink deep into the skin to increase the distance heat has to travel to escape thus reducing heat loss.
Shivering: the muscles in the limbs start to contract and relax rapidly, thus increasing the rate of respiration and amount of heat energy released by it.
Hairs become erect: muscle erectors contract and make the hairs erect and stand up vertically trapping air in the gaps between them. This acts as insulation to reduce heat loss.
How the Body Senses Change in internal environment:
When the body’s internal temperature changes the temperature of the blood changes with it. When the blood flows through the brain, a part of it called the hypothalamus detects the drop or rise in temperature. The brain then starts sending electrical impulses to the rest of the body so that it works on heating or cooling its self.
This process is called Negative Feedback. Negative feedback is not for change in temperature only though, it is for any change in the internal temperature including the blood glucose level.
Regulating Blood Glucose Level:
For blood glucose level however, the pancreas is the organ which monitors its level not the hypothalamus. When the blood flows through the pancreas, the pancreas detects the level of glucose in it. If it is higher than normal, the pancreas secretes a hormone called insulin. Insulin flows in the blood till it reaches the liver. When it reaches the liver, insulin hormone will make it convert excess glucose in the blood into glycogen and store it in the liver cells. When the blood glucose level becomes normal, the pancreas will stop secreting insulin so that the liver stops converting glucose. If the blood glucose level decreases below normal, the pancreas secretes another hormone called glucagon. When glucagon reaches the liver, it makes the liver convert the glycogen it made from excess glucose back into glucose and secrete it into the blood stream so that the blood glucose level goes back to normal. When this happens the pancreas stops secreting glucagon.
Normal Blood Glucose Level: 80-100 mg per 100cm3.
The human body has the ability to maintain a constant internal environment so that every organ and cell is provided the perfect conditions to perform its functions. This is called homeostasis. There is no organ system for this function. However, every organ plays a role in maintaining a constant internal environment. For example the lungs are responsible for the supply of oxygen to cells. The liver is to maintain a constant level of glucose and amino acids, and so on..
Temperature Regulation:
A healthy human should have a body temperature of 37°C. If the body temperature drops below 37°C, metabolic reactions become slower because molecules move slower and have less kinetic energy. If the temperature rises above 37°C, the enzymes of the body begin to get denatured and metabolic reactions will be much slower.
Sometimes, the temperature of the area you are at is low enough to decrease your body temperature. Sometimes it is high enough to raise your body temperature. This is why the body has the ability to control its body temperature. Our skin is responsible for this process. The Human Skin:
The skin is an organ that coats your entire body. The skin is made up of two layers, the Epidermis and the dermis.
The epidermis’s main function is to protect the dermis which contains most of the structures, and protect the body from ultra-violet rays. The surface of the epidermis is made of tough, dead cells.
The dermis contains many useful structures. Hairs, sweat and sebaceous glands, sense receptors and erector muscles are responsible for controlling the body temperature. Blood vessels transport oxygen and nutrients to the cells of the skin.
A healthy body is continuously gaining and losing heat. Metabolic reactions like respiration release a lot of heat energy, muscular activity increase the metabolic rate and release more heat energy. The body can also gain temperature from the surroundings like the sun or by eating hot food. Heat is lost by the body through exposed skin by conduction. If there is sweat or water on the skin, it will absorb body heat to evaporate which drops the temperature. All these factors are normal however, but it is considered dangerous when the body temperature keeps on dropping or rising severely.
Cooling Down the Body:
When the body is overheated, the body takes several actions to drop it by trying to lose heat in several ways:
Vasodilation: this action causes the body to lose heat quickly. It involves widening the lumen of blood vessels of the skin, this increases blood flow and rate of heat loss. The vessels are also brought near the surface of the skin to reduce the distance heat has to travel to escape.
Sweating: Sweat glands near the skin begin to secret sweat on the surface of the skin through the pores. This sweat acts as a heat consumer to absorb the body heat and use it in evaporation. The activity of sweat glands is increased when the temperature of the body rises.
Hairs lie flat: The muscle erectors of the hairs relax making the hairs lay flat of the skin. When the hairs are erect, they trap air in the gaps between them, this acts as an insulation and prevents heat loss. But when the hairs are flat, less air is trapped between them so there is no insulation and more heat can be lost.
Heating Up the Body:
When the body temperatures drop, the body takes several actions to regulate its temperature by insulation to prevent heat loss and producing heat energy:
Vasoconstriction: this causes the blood vessels to become narrower to reduce heat loss. They also sink deep into the skin to increase the distance heat has to travel to escape thus reducing heat loss.
Shivering: the muscles in the limbs start to contract and relax rapidly, thus increasing the rate of respiration and amount of heat energy released by it.
Hairs become erect: muscle erectors contract and make the hairs erect and stand up vertically trapping air in the gaps between them. This acts as insulation to reduce heat loss.
How the Body Senses Change in internal environment:
When the body’s internal temperature changes the temperature of the blood changes with it. When the blood flows through the brain, a part of it called the hypothalamus detects the drop or rise in temperature. The brain then starts sending electrical impulses to the rest of the body so that it works on heating or cooling its self.
This process is called Negative Feedback. Negative feedback is not for change in temperature only though, it is for any change in the internal temperature including the blood glucose level.
Regulating Blood Glucose Level:
For blood glucose level however, the pancreas is the organ which monitors its level not the hypothalamus. When the blood flows through the pancreas, the pancreas detects the level of glucose in it. If it is higher than normal, the pancreas secretes a hormone called insulin. Insulin flows in the blood till it reaches the liver. When it reaches the liver, insulin hormone will make it convert excess glucose in the blood into glycogen and store it in the liver cells. When the blood glucose level becomes normal, the pancreas will stop secreting insulin so that the liver stops converting glucose. If the blood glucose level decreases below normal, the pancreas secretes another hormone called glucagon. When glucagon reaches the liver, it makes the liver convert the glycogen it made from excess glucose back into glucose and secrete it into the blood stream so that the blood glucose level goes back to normal. When this happens the pancreas stops secreting glucagon.
Normal Blood Glucose Level: 80-100 mg per 100cm3.
The mole concept
Moles and Empirical Formula
The Mole Concept:
A mole is a unit to count the number of atoms, ions or molecules. They believed that, for example, if one molecule of carbon dioxide (CO2) contained 1 carbon atom and 2 oxygen atoms, then the ratio of carbon atoms to oxygen atoms is 1:2. So if we wanted to make 100 molecules of carbon dioxide without any excess of the re-actants we will use 200 atoms of oxygen. We got this by:1
Carbon 2
Oxygen
Amount of carbon atoms = 1 x 100 = 100
Amount of oxygen atoms= 2 x 100 = 200
Chemists use a method similar to that one, but on a larger scale, in industries to prevent wasting money by buying excess substances that will not be used. This is called Avogadro’s Constant.
Avogadro’s Constant in Solids:
Avogadro was a scientist in the 19th century. He discovered a relationship between a certain amount of substance (atoms, ions or molecules) and the Ar (Relative atomic mass) or Mr (Relative Molecular Mass) of the substance.The Ar of an element is its Mass Number
in the periodic table. For example:
The Ar of sodium is 23
The Mr of a compound is the sum of the Ar of all the atoms present in one molecule of the compound.The Mr of Carbon dioxide (CO2) is:
The Ar of carbon atom + (2 x the Ar of oxygen atom)
12 + (2 x 16) = 44
So the Mr of carbon dioxide is 44
What Avogadro discovered is that if I am holding 6x1023 atoms in my hand, its mass is equal to the Ar of Iron (Fe).
This unit is called Mole.
6x1023 is not an equation; it is the number of atoms, ions or molecules in one mole. If you put 6x1023 in a calculator, you will find out that this number is 600,000,000,000,000,000,000.
So if I am holding in my hands 600,000,000,000,000,000,000 atoms of iron, then I am holding 1 mole of iron.
This is 56 grams heavy because the Ar of iron is 56.
From this we conclude that the mass of one mole of any substance is the Ar of it (if it was an element) or the Mr of it (if it was a compound). The mass of one mole of any substance is expressed as the molar mass, and the word mole can be abbreviated with mol. The molar mass is always expressed in grams.Molar mass of carbon is 12g
Molar mass of oxygen is 16g
Molar mass of sodium is 23g
Molar mass of iron is 56g
The molar mass of a compound is Mr of it:The molar mass of an oxygen molecule (O2) is: 2x16= 32g
The molar mass of sodium chloride (NaCl) is: 23+35.5= 58.5g
The molar mass of sulphuric acid (H2SO4) is: (2x1)+32+ (4x16) = 98g
The mass of 2 moles of a substance is 2x (Ar or Mr), the mass of 3 moles of a substance is 3x (Ar or Mr)..
The mass of 6 moles of water (H2O) is:
Mr of H2O: (2x1) +16= 18
6mol of (H2O) is: 6x18= 108g
The mass of 9 moles of hydrated copper sulphate (CuSO4.5H2O) is:
Mr of CuSO4.5H2O: 64+32+ (9x16) + (10x1) = 250
9mol of CuSO4.5H2O is: 9x250= 2250g or 2.25kg
If we wanted the mass of a sample of a compound, we had to know its Mr and the numbers of moles of it we have, and multiply both. We can also find the number of moles in a sample of a compound if we know the mass of the sample and the Mr of it.
Remember that the Mr of a substance is how much one mole of it weighs.
How many moles are in 36 grams of water (H2O)?
Mr of water: (2 x 1) + 16 = 18
If one mole of water weighs 18g, then 32g of water must be:
Mole = 32 ÷ 18 = 2mol
How many moles are there in 4 grams of sodium hydroxide (NaOH)?
Mr of NaSO4 = 23 + 16 + 1= 40
Moles = 4 ÷ 40 = 0.1mol
From this we conclude that there is a relation between the mass of a substance, its molar mass, and the number of moles in it.Mass of sample = Moles × Molar Mass (Ar or Mr) Moles = Mass of sample ÷ Molar Mass (Ar or Mr) Molar Mass (Ar or Mr) = Mass of sample ÷ Moles
Avogadro’s Constant in Solutions:
Sometimes we need to find concentration of a solution. The unit of concentration can be g/dm3 or mol/dm3.
Literally, mol/dm3 means how many moles of the solute are dissolved in every dm3 of the solvent. So if salt and water solution has a concentration of 3 mol/dm3, then in every dm3 of water, there are 3 mols of salt dissolved. This means that in order for us to find the concentration of a solution, we divide the amount of solute (in moles) in the solution by the total volume of the solution.
Calculate the concentration (mol/dm3) of a solution containing 4 moles of sulphuric acid and has a volume of 2 dm3.
Concentration = Moles of solute ÷ Volume of solution
Concentration = 4 ÷ 2 = 2 mol/dm3
If we want to find the number of moles dissolved in a solution, we'll need to know both concentration and the volume of the solution.
Find the number of moles of sulphuric acid dissolved in water if the solution has a concentration 2 mol/dm3 and a volume of 25 dm3.
Moles of solute = Concentration x Volume of solution
Moles of solute = 2 x 25 = 50 mol of sulphuric acid
We can also find the volume of a solution, if we know the concentration and number of moles of solute dissolved; we divide the number of moles by the concentration.
Find the volume of a solution containing 4 moles of sulphuric acid with concentration 2 mol/dm3.
Volume of solution = Moles of solute ÷ Concentration
Volume of solution = 4 ÷ 2 = 2dm3
From this we conclude that the relation between the volume, concentration and number of moles dissolved in a solution is:Number of moles = Volume × Concentration Concentration = Number of moles ÷ Volume Volume = Number of moles ÷ Concentration
Avogadro’s Constant in Gases:
In gases it is a different story to solutions and solids because weighing a gas is very difficult, and we have no concentration. So in gases, we use volume of the gas to find how many moles are in it.
Scientists have proved that any gas, will have a volume of 24 dm3 provided that is it is at room temperature and pressure (R.T.P). That means that all gases at r.t.p occupy 24 dm3. We use this theory to find out how many moles are present in some gas if we have its volume, we just divide it by 24.
How many moles of carbon dioxide are there, if the gas occupied 72 dm3?
We know that every 1 mole occupies 24 dm3, so 72 dm3 are occupied by:
Number of moles = Volume of gas ÷ 24
Number of moles = 72 ÷ 24 = 3 mol
We could also find the volume of a gas if we know the number of moles we have in it, we simply multiply it by 24.
What is volume occupied by nitrogen gas, if 6 moles of it are present?
We know that each mole occupies 24dm3 and that we have 6 moles, so they will occupy:
Volume = Number of moles x 24
Volume = 6 x 24 = 144dm3
So we conclude that the relation between the number of moles present in a gas and its volume is:Volume = Number of moles × 24 Number of moles = Volume ÷ 24
Reactions and Mole Ratio:
What volume of carbon dioxide (CO2) at R.T.P will be produced when 50g of calcium carbonate react with an excess of hydrochloric acid:CaCO3 + 2HCl → CaCl2 + H2O + CO2
1 : 2 1 : 1 : 1
First we write the mole ratio of each reactant and product.
Now we find the number of moles in 50g of CaCO3:
Number of moles = Mass ÷ Mr
Number of moles = 50 ÷ 100 = 0.5 mol
If the mole ratio of CaCO3 to CO2 is 1:1, then we must also have 0.5 mol of CO2, if we have 0.5 mol of CO2, then we can get the volume produced:
Volume = Number of moles x 24
Volume = 0.5 x 24 = 12dm3
Volume of CO2 Produced is 12dm3
If all reactants are gases, then the mole ratio is also the volume ratio:
Calculate the volume of methane needed to react with 70 dm3 of oxygen:CH4 + 2O2 → CO2 + 2H2O
1 : 2 1 : 2
First we write the mole ratio of all reactants and products.
If both reactants are gases, then the mole ratio is also the volume ratio, that means if we have 70 dm3 of O2 and the ratio of O2 to CH4 is 2:1, then the volume of CH4 is half the volume of O2:
0.5 x 70 = 35
Volume of methane needed is 35 dm3.
Note: The total mass of the reactants must always equal the total mass of the products.
200g of pure calcium carbonate decomposes to calcium oxide and carbon dioxide. Calculate the mass of CaO produced and the volume of CO2 produced at R.T.P.:CaCO3 → CaO + CO2
1 1 : 1
First we write the mole ratio of the reactant and the products.
Mr of CaCO3 is 40 + 12 + (3 x 16) = 100; moles of CaCO3= 200 ÷ 100 = 2 mols
Then we have 2 mols of CaO, because the mole ratio is 1:1, mass of CaO = 2 x 56 = 112g of CaO is produced.
And if we have 2mols of CO2, because the ratio is 1:1, then the volume of CO2 produced is: 2 x 24 = 48.
48 dm3 of CO2 is produced.
Percentage Purity:
If we have a sample of reactant that is not pure, we can find how pure it is by finding the mass of it that reacted. The impurities are assumed to not interfere with the reaction. Then we divide the mass that reacted by the total mass and multiply it by 100 to get the percentage.Percentage Purity = Pure mass x 100
Total mass
When 10g of impure zinc reacted with dilute sulphuric acid, 2.4 dm3 of hydrogen gas were collected at R.T.P. Calculate the percentage purity of zinc:Zn + H2SO4 → ZnSO4 + H2
1 : 1 1 : 1
First we have to find the number of moles in any of the chemicals in the reaction to find the number of moles of zinc that reacted. We know that we 2.4 dm3 of hydrogen are produced, we can find how many moles this is by:
Number of moles = Volume ÷ 24
Number of moles = 2.4 ÷ 24 = 0.1 mol
If we have 0.1 mol of hydrogen and the mole ratio of hydrogen to zinc is 1:1 then we must also have 0.1 mol of zinc. Now we have to find how much 0.1 mol of zinc weigh:
Mass = Moles x Ar
Mass = 0.1 x 65 = 6.5g
If 6.5g of zinc are present in the sample, then the percentage purity is:
% Purity = (Pure mass ÷ Total mass) x 100
% Purity = (6.5 ÷ 10) x 100 = 65%
Percentage Yield:
Percentage yield is the mass of a substance produced in a reaction as a percentage of the calculated mass. That means that in a reaction, the calculations showed that the 50 grams of calcium oxide will be produced, but practically, only 45 grams were produced then the percentage yield is 45 divided by 50 multiplied by 100, which is 90%:Percentage yield = Mass produced x 100
Mass predicted
Heating 12.4g of Copper (II) Carbonate Produced only 7g of Copper (II) Oxide. Find the percentage yield of Copper (II) Oxide:CuCO3 → CuO + CO2
1 1 : 1
First we calculate the mass of CuO that is supposed to be produced:
We write the mole ratio of the reactant and the products.
Mr of CuCO3 is 124 we have 12.4g so the number of moles is 12.4 ÷ 124 = 0.1; if the ratio of CuCO3 to CuO is 1:1, then we must also have 0.1 mol of CuO, the Mr of CuO is 80. Then the mass of CuO must be 0.1 x 80 = 8g. We actually got 7g so the percentage yield is:
Percentage yield = (Mass produced ÷ Mass predicted) x 100
Percentage yield = (7 ÷ 8) x 100 = 87.5%
So the percentage yield is 87.5%
Composition Percentage of Elements in Compounds:
This is a way to find the percentage of an element in a whole compound. For example, if we have the compound CaCO3, we can find the percentage of any of the elements in it by the following rule:Composition percentage = Number of atoms of the element in a molecule x Ar x 100
Mr of the compound
Find the percentage of nitrogen in the following compounds:
Ammonium Nitrate, NH4NO3:
Ammonium Sulphate, (NH4)2SO4:
Urea, CO(NH2)2:
Answers:
[(14 x 2) ÷ 80] x 100 = 35%
[(14 x 2) ÷ 132] x 100 = 21.21%
[(2 x 14) ÷ 60] x 100 = 46.6%
The Empirical Formula:
The molecular formula shows the actual number of atoms of each element in a compound, but the empirical formula is a formula that shows the simplest ratio of atoms present in a compound. For example if a compound has the molecular formula C4H8, its empirical formula would be(CH2)n, n is the number to multiply by to get the molecular formula, which is 4 in this case, the 8 is divided by the 4 to give the simplest ratio between them. The empirical formula is widely used with hydrocarbons which are compounds containing hydrogen and carbon, and carbohydrates, which are compounds containing carbon and water.
A carbohydrate has 40% of its mass carbon, 6.66% hydrogen. Find the compound’s empirical and molecular formula given that is Mr is 180:
We assume that we’ve got 100g of this carbohydrate. Then we have 40g of carbon and 6.66g of hydrogen, we can now find oxygen’s mass and the number of moles we have of each element, thus we can get the simplest ratio between them and get the empirical formula. Carbon Hydrogen Oxygen
Mass % 40 6.66 100 - 46.6 = 53.34
Ar 12 1 16
Moles (40 ÷ 12) = 3.33 (6.66 ÷ 1) = 6.66 (53.34 ÷ 16) = 3.33
Simple ratio 1 2 1
Empirical formula C H2 O
Emperical formula: CH2O
N = Molecular Mr ÷ Empirical Mr
N = 180 ÷ 30 = 6
Molecular Formula = C6H12O6
The Mole Concept:
A mole is a unit to count the number of atoms, ions or molecules. They believed that, for example, if one molecule of carbon dioxide (CO2) contained 1 carbon atom and 2 oxygen atoms, then the ratio of carbon atoms to oxygen atoms is 1:2. So if we wanted to make 100 molecules of carbon dioxide without any excess of the re-actants we will use 200 atoms of oxygen. We got this by:1
Carbon 2
Oxygen
Amount of carbon atoms = 1 x 100 = 100
Amount of oxygen atoms= 2 x 100 = 200
Chemists use a method similar to that one, but on a larger scale, in industries to prevent wasting money by buying excess substances that will not be used. This is called Avogadro’s Constant.
Avogadro’s Constant in Solids:
Avogadro was a scientist in the 19th century. He discovered a relationship between a certain amount of substance (atoms, ions or molecules) and the Ar (Relative atomic mass) or Mr (Relative Molecular Mass) of the substance.The Ar of an element is its Mass Number
in the periodic table. For example:
The Ar of sodium is 23
The Mr of a compound is the sum of the Ar of all the atoms present in one molecule of the compound.The Mr of Carbon dioxide (CO2) is:
The Ar of carbon atom + (2 x the Ar of oxygen atom)
12 + (2 x 16) = 44
So the Mr of carbon dioxide is 44
What Avogadro discovered is that if I am holding 6x1023 atoms in my hand, its mass is equal to the Ar of Iron (Fe).
This unit is called Mole.
6x1023 is not an equation; it is the number of atoms, ions or molecules in one mole. If you put 6x1023 in a calculator, you will find out that this number is 600,000,000,000,000,000,000.
So if I am holding in my hands 600,000,000,000,000,000,000 atoms of iron, then I am holding 1 mole of iron.
This is 56 grams heavy because the Ar of iron is 56.
From this we conclude that the mass of one mole of any substance is the Ar of it (if it was an element) or the Mr of it (if it was a compound). The mass of one mole of any substance is expressed as the molar mass, and the word mole can be abbreviated with mol. The molar mass is always expressed in grams.Molar mass of carbon is 12g
Molar mass of oxygen is 16g
Molar mass of sodium is 23g
Molar mass of iron is 56g
The molar mass of a compound is Mr of it:The molar mass of an oxygen molecule (O2) is: 2x16= 32g
The molar mass of sodium chloride (NaCl) is: 23+35.5= 58.5g
The molar mass of sulphuric acid (H2SO4) is: (2x1)+32+ (4x16) = 98g
The mass of 2 moles of a substance is 2x (Ar or Mr), the mass of 3 moles of a substance is 3x (Ar or Mr)..
The mass of 6 moles of water (H2O) is:
Mr of H2O: (2x1) +16= 18
6mol of (H2O) is: 6x18= 108g
The mass of 9 moles of hydrated copper sulphate (CuSO4.5H2O) is:
Mr of CuSO4.5H2O: 64+32+ (9x16) + (10x1) = 250
9mol of CuSO4.5H2O is: 9x250= 2250g or 2.25kg
If we wanted the mass of a sample of a compound, we had to know its Mr and the numbers of moles of it we have, and multiply both. We can also find the number of moles in a sample of a compound if we know the mass of the sample and the Mr of it.
Remember that the Mr of a substance is how much one mole of it weighs.
How many moles are in 36 grams of water (H2O)?
Mr of water: (2 x 1) + 16 = 18
If one mole of water weighs 18g, then 32g of water must be:
Mole = 32 ÷ 18 = 2mol
How many moles are there in 4 grams of sodium hydroxide (NaOH)?
Mr of NaSO4 = 23 + 16 + 1= 40
Moles = 4 ÷ 40 = 0.1mol
From this we conclude that there is a relation between the mass of a substance, its molar mass, and the number of moles in it.Mass of sample = Moles × Molar Mass (Ar or Mr) Moles = Mass of sample ÷ Molar Mass (Ar or Mr) Molar Mass (Ar or Mr) = Mass of sample ÷ Moles
Avogadro’s Constant in Solutions:
Sometimes we need to find concentration of a solution. The unit of concentration can be g/dm3 or mol/dm3.
Literally, mol/dm3 means how many moles of the solute are dissolved in every dm3 of the solvent. So if salt and water solution has a concentration of 3 mol/dm3, then in every dm3 of water, there are 3 mols of salt dissolved. This means that in order for us to find the concentration of a solution, we divide the amount of solute (in moles) in the solution by the total volume of the solution.
Calculate the concentration (mol/dm3) of a solution containing 4 moles of sulphuric acid and has a volume of 2 dm3.
Concentration = Moles of solute ÷ Volume of solution
Concentration = 4 ÷ 2 = 2 mol/dm3
If we want to find the number of moles dissolved in a solution, we'll need to know both concentration and the volume of the solution.
Find the number of moles of sulphuric acid dissolved in water if the solution has a concentration 2 mol/dm3 and a volume of 25 dm3.
Moles of solute = Concentration x Volume of solution
Moles of solute = 2 x 25 = 50 mol of sulphuric acid
We can also find the volume of a solution, if we know the concentration and number of moles of solute dissolved; we divide the number of moles by the concentration.
Find the volume of a solution containing 4 moles of sulphuric acid with concentration 2 mol/dm3.
Volume of solution = Moles of solute ÷ Concentration
Volume of solution = 4 ÷ 2 = 2dm3
From this we conclude that the relation between the volume, concentration and number of moles dissolved in a solution is:Number of moles = Volume × Concentration Concentration = Number of moles ÷ Volume Volume = Number of moles ÷ Concentration
Avogadro’s Constant in Gases:
In gases it is a different story to solutions and solids because weighing a gas is very difficult, and we have no concentration. So in gases, we use volume of the gas to find how many moles are in it.
Scientists have proved that any gas, will have a volume of 24 dm3 provided that is it is at room temperature and pressure (R.T.P). That means that all gases at r.t.p occupy 24 dm3. We use this theory to find out how many moles are present in some gas if we have its volume, we just divide it by 24.
How many moles of carbon dioxide are there, if the gas occupied 72 dm3?
We know that every 1 mole occupies 24 dm3, so 72 dm3 are occupied by:
Number of moles = Volume of gas ÷ 24
Number of moles = 72 ÷ 24 = 3 mol
We could also find the volume of a gas if we know the number of moles we have in it, we simply multiply it by 24.
What is volume occupied by nitrogen gas, if 6 moles of it are present?
We know that each mole occupies 24dm3 and that we have 6 moles, so they will occupy:
Volume = Number of moles x 24
Volume = 6 x 24 = 144dm3
So we conclude that the relation between the number of moles present in a gas and its volume is:Volume = Number of moles × 24 Number of moles = Volume ÷ 24
Reactions and Mole Ratio:
What volume of carbon dioxide (CO2) at R.T.P will be produced when 50g of calcium carbonate react with an excess of hydrochloric acid:CaCO3 + 2HCl → CaCl2 + H2O + CO2
1 : 2 1 : 1 : 1
First we write the mole ratio of each reactant and product.
Now we find the number of moles in 50g of CaCO3:
Number of moles = Mass ÷ Mr
Number of moles = 50 ÷ 100 = 0.5 mol
If the mole ratio of CaCO3 to CO2 is 1:1, then we must also have 0.5 mol of CO2, if we have 0.5 mol of CO2, then we can get the volume produced:
Volume = Number of moles x 24
Volume = 0.5 x 24 = 12dm3
Volume of CO2 Produced is 12dm3
If all reactants are gases, then the mole ratio is also the volume ratio:
Calculate the volume of methane needed to react with 70 dm3 of oxygen:CH4 + 2O2 → CO2 + 2H2O
1 : 2 1 : 2
First we write the mole ratio of all reactants and products.
If both reactants are gases, then the mole ratio is also the volume ratio, that means if we have 70 dm3 of O2 and the ratio of O2 to CH4 is 2:1, then the volume of CH4 is half the volume of O2:
0.5 x 70 = 35
Volume of methane needed is 35 dm3.
Note: The total mass of the reactants must always equal the total mass of the products.
200g of pure calcium carbonate decomposes to calcium oxide and carbon dioxide. Calculate the mass of CaO produced and the volume of CO2 produced at R.T.P.:CaCO3 → CaO + CO2
1 1 : 1
First we write the mole ratio of the reactant and the products.
Mr of CaCO3 is 40 + 12 + (3 x 16) = 100; moles of CaCO3= 200 ÷ 100 = 2 mols
Then we have 2 mols of CaO, because the mole ratio is 1:1, mass of CaO = 2 x 56 = 112g of CaO is produced.
And if we have 2mols of CO2, because the ratio is 1:1, then the volume of CO2 produced is: 2 x 24 = 48.
48 dm3 of CO2 is produced.
Percentage Purity:
If we have a sample of reactant that is not pure, we can find how pure it is by finding the mass of it that reacted. The impurities are assumed to not interfere with the reaction. Then we divide the mass that reacted by the total mass and multiply it by 100 to get the percentage.Percentage Purity = Pure mass x 100
Total mass
When 10g of impure zinc reacted with dilute sulphuric acid, 2.4 dm3 of hydrogen gas were collected at R.T.P. Calculate the percentage purity of zinc:Zn + H2SO4 → ZnSO4 + H2
1 : 1 1 : 1
First we have to find the number of moles in any of the chemicals in the reaction to find the number of moles of zinc that reacted. We know that we 2.4 dm3 of hydrogen are produced, we can find how many moles this is by:
Number of moles = Volume ÷ 24
Number of moles = 2.4 ÷ 24 = 0.1 mol
If we have 0.1 mol of hydrogen and the mole ratio of hydrogen to zinc is 1:1 then we must also have 0.1 mol of zinc. Now we have to find how much 0.1 mol of zinc weigh:
Mass = Moles x Ar
Mass = 0.1 x 65 = 6.5g
If 6.5g of zinc are present in the sample, then the percentage purity is:
% Purity = (Pure mass ÷ Total mass) x 100
% Purity = (6.5 ÷ 10) x 100 = 65%
Percentage Yield:
Percentage yield is the mass of a substance produced in a reaction as a percentage of the calculated mass. That means that in a reaction, the calculations showed that the 50 grams of calcium oxide will be produced, but practically, only 45 grams were produced then the percentage yield is 45 divided by 50 multiplied by 100, which is 90%:Percentage yield = Mass produced x 100
Mass predicted
Heating 12.4g of Copper (II) Carbonate Produced only 7g of Copper (II) Oxide. Find the percentage yield of Copper (II) Oxide:CuCO3 → CuO + CO2
1 1 : 1
First we calculate the mass of CuO that is supposed to be produced:
We write the mole ratio of the reactant and the products.
Mr of CuCO3 is 124 we have 12.4g so the number of moles is 12.4 ÷ 124 = 0.1; if the ratio of CuCO3 to CuO is 1:1, then we must also have 0.1 mol of CuO, the Mr of CuO is 80. Then the mass of CuO must be 0.1 x 80 = 8g. We actually got 7g so the percentage yield is:
Percentage yield = (Mass produced ÷ Mass predicted) x 100
Percentage yield = (7 ÷ 8) x 100 = 87.5%
So the percentage yield is 87.5%
Composition Percentage of Elements in Compounds:
This is a way to find the percentage of an element in a whole compound. For example, if we have the compound CaCO3, we can find the percentage of any of the elements in it by the following rule:Composition percentage = Number of atoms of the element in a molecule x Ar x 100
Mr of the compound
Find the percentage of nitrogen in the following compounds:
Ammonium Nitrate, NH4NO3:
Ammonium Sulphate, (NH4)2SO4:
Urea, CO(NH2)2:
Answers:
[(14 x 2) ÷ 80] x 100 = 35%
[(14 x 2) ÷ 132] x 100 = 21.21%
[(2 x 14) ÷ 60] x 100 = 46.6%
The Empirical Formula:
The molecular formula shows the actual number of atoms of each element in a compound, but the empirical formula is a formula that shows the simplest ratio of atoms present in a compound. For example if a compound has the molecular formula C4H8, its empirical formula would be(CH2)n, n is the number to multiply by to get the molecular formula, which is 4 in this case, the 8 is divided by the 4 to give the simplest ratio between them. The empirical formula is widely used with hydrocarbons which are compounds containing hydrogen and carbon, and carbohydrates, which are compounds containing carbon and water.
A carbohydrate has 40% of its mass carbon, 6.66% hydrogen. Find the compound’s empirical and molecular formula given that is Mr is 180:
We assume that we’ve got 100g of this carbohydrate. Then we have 40g of carbon and 6.66g of hydrogen, we can now find oxygen’s mass and the number of moles we have of each element, thus we can get the simplest ratio between them and get the empirical formula. Carbon Hydrogen Oxygen
Mass % 40 6.66 100 - 46.6 = 53.34
Ar 12 1 16
Moles (40 ÷ 12) = 3.33 (6.66 ÷ 1) = 6.66 (53.34 ÷ 16) = 3.33
Simple ratio 1 2 1
Empirical formula C H2 O
Emperical formula: CH2O
N = Molecular Mr ÷ Empirical Mr
N = 180 ÷ 30 = 6
Molecular Formula = C6H12O6
Acids, Bases and Slats
All substances are acidic, neutral or basic (alkaline). How acidic or basic a substance is shown by its pH. There are several other ways by which we could find out whether a substance is acidic, neutral or basic.
pH Scale:
This is a scale that runs from 0 to 14. Substances with a pH below 7 are acidic. Substances with pH above 7 are basic. And those with pH 7 are neutral.
Indicators:
Indicators are substances that identify acidity or alkalinity of substances. They cannot be used in solid form.
Universal Indicator:
This is a substance that changes color when added to another substance depending on its pH. The indicator and the substance should be in aqueous form.
Litmus Paper or Solution:
This indicator is present in two colors: red and blue. We use blue litmus if we want test a substance for acidity. We use red litmus if we want to test a substance for alkalinity. Its results are:
Acids: Turns blue litmus paper/ solution red,
Bases: Turns red litmus paper/ solution blue,
Neutral: if it is used as paper the color doesn’t change. If it is used as solution it turns purple.
Note: use damp litmus paper if testing gases.
Phenolphthalein:
This is an indicator that is used to test for alkalinity because it is colorless if used with an acidic or neutral substance and it is pink if it is used with a basic substance.
Methyl Orange:
This indicator gives fire colors: Red with acids, yellow with neutrals and orange with bases.
Acids:
Acids are substances made of a hydrogen ion and non-metal ions. They have the following properties:
They dissolve in water producing a hydrogen ion H+,
They have a sour taste,
Strong ones are corrosive,
Their pH is less than 7.
All acids must be in aqueous form to be called an acid. For example Hydrochloric acid is hydrogen chloride gas dissolved in water. The most common acids are:
Hydrochloric acid HCl,
Sulphuric Acid H2SO4,
Nitric Acid HNO3,
Cirtric Acid,
Carbonic Acid H2CO3.
Strength of Acids:
One of the most important properties of acids is that it gives hydrogen ion H+ when dissolved in water. This is why the amount of H+ ions the acid can give when dissolved in water is what determines its strength. This is called ionization or dissociation. The more ionized the acid is the stronger it is, the lower its pH. The more H+ ions given when the acid is dissolved in water the more ionized the acid is.
Strong Acids:
Have pH’s: 0,1,2,3
They are fully ionized
When dissolved in water, they give large amounts of H+ ions
Examples:
Hydrochloric Acid
Sulfuric Acid
Nitric Acid
Weak Acids:
Have pH’s: 4,5,6
They are partially ionized
When dissolved in water, they give small amounts of H+ ions
Examples:
Ethanoic acid (CH3COOH)
Citric Acid
Carbonic Acid
Hydrochloric acid is a strong acid. When it is dissolved in water all HCl molecules are ionized into H+ and Cl- ions. It is fully ionized.
Ethanoic acid has the formula CH3COOH. It is a weak acid. When it is dissolved in water, only some of the CH3COOH molecules are ionized into CH3COO- and H+ ions. It is partially ionized.
Note: Acids with pH 3 or 4 can be considered moderate in strength.
Solutions of strong acids are better conductors of electricity than solutions of weak acids. This is because they contain much more free mobile ions to carry the charge.
Concentrated acids are not necessarily strong. The concentration of an acid only means the amount of molecules of the acid dissolved in water. Concentrated acids have a large amount of acid molecules dissolved in water. Dilute acids have a small amount of acid molecules dissolved in water. Concentration is not related to strength of the acids. Strong acids are still strong even if they are diluted. And weak acids are still weak even if they are concentrated.
Bases:
Bases are substances made of hydroxide OH- ions and a metal. Bases can be made of:
Metal hydroxide (metal ion & OH- ion)
Metal oxides
Metal carbonates (metal ion & CO32-)
Metal hydrogen carbonate (Bicarbonate)
Ammonium hydroxide (NH4OH)
Ammonium Carbonate ((NH4)2CO3)
Properties of bases:
Bitter taste
Soapy feel
Have pH’s above 7
Strong ones are corrosive
Some bases are water soluble and some bases are water insoluble. Water soluble bases are also called alkalis.
Like acids, alkalis' strength is determined by its ability to be ionized into metal and hydroxide OH- ions. Completely ionized alkalis are the strongest and partially ionized alkalis are the weakest. Ammonium hydroxide is one of the strongest alkalis while weak alkalis include the hydroxides of sodium, potassium and magnesium.
Types of Oxides:
Basic Oxides
They are metal oxides
They react with acids forming a salt and water
They are solids
They are insoluble in water except group 1 metal oxides.
They react with an acid forming salt and water
Examples: Na2O, CaO and CuO
Amphoteric Oxides
These are oxides of Aluminum, Zinc & Lead
They act as an acid when reacting with an alkali & vice versa
Their element’s hydroxides are amphoteric too
They produce salt and water when reacting with an acid or an alkali.
Acidic Oxides
They are all non-metal oxides except non-metal monoxides
They are gases
They react with an alkali to form salt and water
Note: metal monoxides are neutral oxides
Examples: CO2, NO2, SO2 (acidic oxides) & CO, NO,
H2O (neutral oxides)
Salts:
A salt is a neutral ionic compound. Salts are one of the products of a reaction between an acid and a base. Salts are formed in reactions I n which the H+ ion from the acid is replaced by any other metal ion. Some salts are soluble in water and some are insoluble.
Soluble Salts:
All Nitrates
All halides EXCEPT AgCl and PbCl2
All sulfates EXCEPT CaSO4, BASO4, PbSO4
All group 1 metals salts
All ammonium salts
Insoluble Salts:
Silver and lead chlorides (AgCl & PbCl2)
Calcium, barium and lead sulphates (CaSO4, BASO4, PbSO4)
All carbonates EXCEPT group 1 metals and ammonium carbonates
Preparing Soluble Salts:
Displacement Method (Excess Metal Method):
Metal + Acid → Salt + Hydrogen
Note: this type of method is suitable to for making salts of moderately reactive metals because highly reactive metals like K, Na and Ca will cause an explosion. This method is used with the MAZIT (Magnesium, Aluminum, Zinc, Iron and Tin) metals only.
Example: set up an experiment to obtain magnesium chloride salt.
Mg + 2HCl → MgCl2 + H2
Add 100 cm3 of dilute hydrochloric acid to a beaker
Add excess mass of powdered magnesium
When the reaction is done, filter the mixture to get rid of excess magnesium (residue)
The filtrate is magnesium chloride solution
To obtain magnesium chloride powder, evaporate the solution till dryness
To obtain magnesium chloride crystals, heat the solution while continuously dipping a glass rod in the solution
When you observe crystals starting to form on the glass rod, turn heat off and leave the mixture to cool down slowly
When the crystals are obtained, dry them between two filter papers
Observations of this type of reactions:
Bubbles of colorless gas evolve (hydrogen). To test approach a lighted splint if hydrogen is present it makes a pop sound
The temperature rises (exothermic reaction)
The metal disappears
You know the reaction is over when:
No more gas evolves
No more magnesium can dissolve
The temperature stops rising
The solution becomes neutral
Proton Donor and Acceptor Theory:
When an acid and a base react, water is formed. The acid gives away an H+ ion and the base accepts it to form water by bonding it with the OH- ion. A hydrogen ion is also called a proton this is why an acid can be called Proton Donor and a base can be called Proton Acceptor.
Neutralization Method:
Acis + Base → Salt + Water
Note: This method is used to make salts of metals below hydrogen in the reactivity series. If the base is a metal oxide or metal hydroxide, the products will be salt and water only. If the base is a metal carbonate, the products will be salt, water and carbon dioxide.
Type 1:
Acid + Metal Oxide → Salt + Water
To obtain copper sulfate salt given copper oxide and sulfuric acid:
CuO + H2SO4 → CuSO4 + H2O
Add 100 cm3 of sulfuric acid to a beaker
Add excess mass of Copper oxide
When the reaction is over, filter the excess copper oxide off
The filtrate is a copper sulfate solution, to obtain copper sulfate powder evaporate the solution till dryness
To obtain copper sulfate crystals, heat the solution white continuously dipping a glass rod in it
When you observe crystals starting to form on the glass rod, turn heat of and leave the mixture to cool down slowly
When you obtain the crystals dry them between two filter papers
Observations of this reaction:
The amount of copper oxide decreases
The solution changes color from colorless to blue
The temperature rises
You know the reaction is over when
No more copper oxide dissolves
The temperature stops rising
The solution become neutral
Type 2:
Acid + Metal Hydroxide → Salt + Water
to obtain sodium chloride crystals given sodium hydroxide and hydrochloric acid:
HCl + NaOH → NaCl + H2O
Add 100 cm3of dilute hydrochloric acid to a beaker
Add excess mass of sodium hydroxide
When the reaction is over, filter the excess sodium hydroxide off
The filtrate is sodium chloride solution, to obtain sodium chloride powder, evaporate the solution till dryness
To obtain sodium chloride crystals, hear the solution while continuously dipping a glass rod in it
When crystals start to form on the glass rod, turn heat off and leave the mixture to cool down slowly
When the crystals are obtained, dry them between two filter papers
Observations:
Sodium hydroxide starts disappearing
Temperature rises
You know the reaction is over when:
The temperature stops rising
No more sodium hydroxide can dissolve
The pH of the solution becomes neutral
Type 3:
Acid + Metal Carbonate → Salt + Water + Carbon Dioxide
To obtain copper sulfate salt given copper carbonate and sulfuric acid:
CuCO3 + H2SO4 → CuSO4 + H2O + CO2
Add 100 cm3 of dilute sulfuric acid to a beaker
Add excess mass of copper carbonate
When the reaction is over, filter excess copper carbonate off
The filtrate is a copper sulfate solution, to obtain copper sulfate powder evaporate the solution till dryness
To obtain copper sulfate crystals, heat the solution white continuously dipping a glass rod in it
When you observe crystals starting to form on the glass rod, turn heat of and leave the mixture to cool down slowly
When you obtain the crystals dry them between two filter papers
Observations:
Bubbles of colorless gas (carbon dioxide) evolve, test by approaching lighted splint, if the CO2 is present the flame will be put off
Green Copper carbonate starts to disappear
The temperature rises
The solution turns blue
You know the reaction is finished when:
No more bubbles are evolving
The temperature stops rising
No more copper carbonate can dissolve
The pH of the solution becomes neutral Titration Method:
This is a method to make a neutralization reaction between a base and an acid producing a salt without any excess. In this method, the experiment is preformed twice, the first time is to find the amounts of reactants to use, and the second experiment is the actual one.
1st Experiment:
Add 50 cm3 of sodium hydroxide using a pipette to be accurate to flask
Add 5 drops of phenolphthalein indicator to the sodium hydroxide. The solution turns pink indicating presence of a base
Fill a burette to zero mark with hydrochloric acid
Add drops of the acid to conical flask
The pink color of the solution becomes lighter
When the solution turns colorless, stop adding the acid (End point: is the point at which every base molecule is neutralized by an acid molecule)
Record the amount of hydrochloric acid used and repeat the experiment without using the indicator
After the 2nd experiment, you will have a sodium chloride solution. Evaporate it till dryness to obtain powdered sodium chloride or crystalize it to obtain sodium chloride crystals
Preparing Insoluble Salts:
Precipitation Method:
A precipitation reaction is a reaction between two soluble salts. The products of a precipitation reaction are two other salts, one of them is soluble and one is insoluble (precipitate).
Example: To obtain barium sulfate salt given barium chloride and sodium sulfate:
BaCl2 + Na2SO4 → BaSO4 + 2NaCl
Ionic Equation: Ba2+ + SO42- → BaSO4
Add the two salt solutions in a beaker
When the reaction is over, filter and take the residue
Wash the residue with distilled water and dry it in the oven
Observations:
Temperature increases
An insoluble solid precipitate (Barium sulfate) forms
You know the reaction is over when:
The temperature stops rising
No more precipitate is being formed
Controlling Soil pH:
If the pH of the soil goes below or above 7, it has to be neutralized using an acid or a base. If the pH of the soil goes below 7, calcium carbonate (lime stone) is used to neutralize it. The pH of the soil can be measured by taking a sample from the soil, crushing it, dissolving in water then measuring the pH of the solution.
Colors of Salts:Salt Formula Solid In Solution
Hydrated copper sulfate CuSO4.5H2O Blue crystals Blue
Anhydrous copper sulfate CuSO4 White powder Blue
Copper nitrate Cu(NO3)2 Blue crystals Blue
Copper chloride CuCl2 Green Green
Copper carbonate CuCO3 Green Insoluble
Copper oxide CuO Black Insoluble
Iron(II) salts E.g.: FeSO4, Fe(NO3)2 Pale green crystals Pale green
Iron(III) salts E.g.: Fe(NO3)3 Reddish brown Reddish brown
Tests for Gases:Gas Formula Tests
Ammonia NH3 Turns damp red litmus paper blue
Carbon dioxide CO2 Turns limewater milky
Oxygen O2 Relights a glowing splint
Hydrogen H2 ‘Pops’ with a lighted splint
Chlorine Cl2 Bleaches damp litmus paper
Nitrogen dioxide NO2 Turns damp blue litmus paper red
Sulfur dioxide SO2 Turns acidified aqueous potassium dichromate(VI) from orange to green
Tests for Anions:Anion Test Result
Carbonate (CO32-) Add dilute acid Effervescence,
carbon dioxide produced
Chloride (Cl-)
(in solution) Acidify with dilute nitric acid, then add
aqueous silver nitrate White ppt.
Iodide (I-)
(in solution) Acidify with dilute nitric acid, then add
aqueous silver nitrate Yellow ppt.
Nitrate (NO3-)
(in solution) Add aqueous sodium hydroxide, then
aluminium foil; warm carefully Ammonia produced
Sulfate (SO42-) Acidify, then add aqueous barium nitrate White ppt.
Tests for aqueous cations:Cation Effect of aqueous sodium hydroxide Effect of aqueous ammonia
Aluminium (Al3+) White ppt., soluble in excess giving a
colourless solution White ppt., insoluble in excess
Ammonium (NH4+) Ammonia produced on warming –
Calcium (Ca2+) White ppt., insoluble in excess No ppt. or very slight white ppt.
Copper (Cu2+) Light blue ppt., insoluble in excess Light blue ppt., soluble in excess,
giving a dark blue solution
Iron(II) (Fe2+) Green ppt., insoluble in excess Green ppt., insoluble in excess
Iron(III) (Fe3+) Red-brown ppt., insoluble in excess Red-brown ppt., insoluble in excess
Zinc (Zn2+) White ppt., soluble in excess,
giving a colourless solution White ppt., soluble in excess,
giving a colourless solution
pH Scale:
This is a scale that runs from 0 to 14. Substances with a pH below 7 are acidic. Substances with pH above 7 are basic. And those with pH 7 are neutral.
Indicators:
Indicators are substances that identify acidity or alkalinity of substances. They cannot be used in solid form.
Universal Indicator:
This is a substance that changes color when added to another substance depending on its pH. The indicator and the substance should be in aqueous form.
Litmus Paper or Solution:
This indicator is present in two colors: red and blue. We use blue litmus if we want test a substance for acidity. We use red litmus if we want to test a substance for alkalinity. Its results are:
Acids: Turns blue litmus paper/ solution red,
Bases: Turns red litmus paper/ solution blue,
Neutral: if it is used as paper the color doesn’t change. If it is used as solution it turns purple.
Note: use damp litmus paper if testing gases.
Phenolphthalein:
This is an indicator that is used to test for alkalinity because it is colorless if used with an acidic or neutral substance and it is pink if it is used with a basic substance.
Methyl Orange:
This indicator gives fire colors: Red with acids, yellow with neutrals and orange with bases.
Acids:
Acids are substances made of a hydrogen ion and non-metal ions. They have the following properties:
They dissolve in water producing a hydrogen ion H+,
They have a sour taste,
Strong ones are corrosive,
Their pH is less than 7.
All acids must be in aqueous form to be called an acid. For example Hydrochloric acid is hydrogen chloride gas dissolved in water. The most common acids are:
Hydrochloric acid HCl,
Sulphuric Acid H2SO4,
Nitric Acid HNO3,
Cirtric Acid,
Carbonic Acid H2CO3.
Strength of Acids:
One of the most important properties of acids is that it gives hydrogen ion H+ when dissolved in water. This is why the amount of H+ ions the acid can give when dissolved in water is what determines its strength. This is called ionization or dissociation. The more ionized the acid is the stronger it is, the lower its pH. The more H+ ions given when the acid is dissolved in water the more ionized the acid is.
Strong Acids:
Have pH’s: 0,1,2,3
They are fully ionized
When dissolved in water, they give large amounts of H+ ions
Examples:
Hydrochloric Acid
Sulfuric Acid
Nitric Acid
Weak Acids:
Have pH’s: 4,5,6
They are partially ionized
When dissolved in water, they give small amounts of H+ ions
Examples:
Ethanoic acid (CH3COOH)
Citric Acid
Carbonic Acid
Hydrochloric acid is a strong acid. When it is dissolved in water all HCl molecules are ionized into H+ and Cl- ions. It is fully ionized.
Ethanoic acid has the formula CH3COOH. It is a weak acid. When it is dissolved in water, only some of the CH3COOH molecules are ionized into CH3COO- and H+ ions. It is partially ionized.
Note: Acids with pH 3 or 4 can be considered moderate in strength.
Solutions of strong acids are better conductors of electricity than solutions of weak acids. This is because they contain much more free mobile ions to carry the charge.
Concentrated acids are not necessarily strong. The concentration of an acid only means the amount of molecules of the acid dissolved in water. Concentrated acids have a large amount of acid molecules dissolved in water. Dilute acids have a small amount of acid molecules dissolved in water. Concentration is not related to strength of the acids. Strong acids are still strong even if they are diluted. And weak acids are still weak even if they are concentrated.
Bases:
Bases are substances made of hydroxide OH- ions and a metal. Bases can be made of:
Metal hydroxide (metal ion & OH- ion)
Metal oxides
Metal carbonates (metal ion & CO32-)
Metal hydrogen carbonate (Bicarbonate)
Ammonium hydroxide (NH4OH)
Ammonium Carbonate ((NH4)2CO3)
Properties of bases:
Bitter taste
Soapy feel
Have pH’s above 7
Strong ones are corrosive
Some bases are water soluble and some bases are water insoluble. Water soluble bases are also called alkalis.
Like acids, alkalis' strength is determined by its ability to be ionized into metal and hydroxide OH- ions. Completely ionized alkalis are the strongest and partially ionized alkalis are the weakest. Ammonium hydroxide is one of the strongest alkalis while weak alkalis include the hydroxides of sodium, potassium and magnesium.
Types of Oxides:
Basic Oxides
They are metal oxides
They react with acids forming a salt and water
They are solids
They are insoluble in water except group 1 metal oxides.
They react with an acid forming salt and water
Examples: Na2O, CaO and CuO
Amphoteric Oxides
These are oxides of Aluminum, Zinc & Lead
They act as an acid when reacting with an alkali & vice versa
Their element’s hydroxides are amphoteric too
They produce salt and water when reacting with an acid or an alkali.
Acidic Oxides
They are all non-metal oxides except non-metal monoxides
They are gases
They react with an alkali to form salt and water
Note: metal monoxides are neutral oxides
Examples: CO2, NO2, SO2 (acidic oxides) & CO, NO,
H2O (neutral oxides)
Salts:
A salt is a neutral ionic compound. Salts are one of the products of a reaction between an acid and a base. Salts are formed in reactions I n which the H+ ion from the acid is replaced by any other metal ion. Some salts are soluble in water and some are insoluble.
Soluble Salts:
All Nitrates
All halides EXCEPT AgCl and PbCl2
All sulfates EXCEPT CaSO4, BASO4, PbSO4
All group 1 metals salts
All ammonium salts
Insoluble Salts:
Silver and lead chlorides (AgCl & PbCl2)
Calcium, barium and lead sulphates (CaSO4, BASO4, PbSO4)
All carbonates EXCEPT group 1 metals and ammonium carbonates
Preparing Soluble Salts:
Displacement Method (Excess Metal Method):
Metal + Acid → Salt + Hydrogen
Note: this type of method is suitable to for making salts of moderately reactive metals because highly reactive metals like K, Na and Ca will cause an explosion. This method is used with the MAZIT (Magnesium, Aluminum, Zinc, Iron and Tin) metals only.
Example: set up an experiment to obtain magnesium chloride salt.
Mg + 2HCl → MgCl2 + H2
Add 100 cm3 of dilute hydrochloric acid to a beaker
Add excess mass of powdered magnesium
When the reaction is done, filter the mixture to get rid of excess magnesium (residue)
The filtrate is magnesium chloride solution
To obtain magnesium chloride powder, evaporate the solution till dryness
To obtain magnesium chloride crystals, heat the solution while continuously dipping a glass rod in the solution
When you observe crystals starting to form on the glass rod, turn heat off and leave the mixture to cool down slowly
When the crystals are obtained, dry them between two filter papers
Observations of this type of reactions:
Bubbles of colorless gas evolve (hydrogen). To test approach a lighted splint if hydrogen is present it makes a pop sound
The temperature rises (exothermic reaction)
The metal disappears
You know the reaction is over when:
No more gas evolves
No more magnesium can dissolve
The temperature stops rising
The solution becomes neutral
Proton Donor and Acceptor Theory:
When an acid and a base react, water is formed. The acid gives away an H+ ion and the base accepts it to form water by bonding it with the OH- ion. A hydrogen ion is also called a proton this is why an acid can be called Proton Donor and a base can be called Proton Acceptor.
Neutralization Method:
Acis + Base → Salt + Water
Note: This method is used to make salts of metals below hydrogen in the reactivity series. If the base is a metal oxide or metal hydroxide, the products will be salt and water only. If the base is a metal carbonate, the products will be salt, water and carbon dioxide.
Type 1:
Acid + Metal Oxide → Salt + Water
To obtain copper sulfate salt given copper oxide and sulfuric acid:
CuO + H2SO4 → CuSO4 + H2O
Add 100 cm3 of sulfuric acid to a beaker
Add excess mass of Copper oxide
When the reaction is over, filter the excess copper oxide off
The filtrate is a copper sulfate solution, to obtain copper sulfate powder evaporate the solution till dryness
To obtain copper sulfate crystals, heat the solution white continuously dipping a glass rod in it
When you observe crystals starting to form on the glass rod, turn heat of and leave the mixture to cool down slowly
When you obtain the crystals dry them between two filter papers
Observations of this reaction:
The amount of copper oxide decreases
The solution changes color from colorless to blue
The temperature rises
You know the reaction is over when
No more copper oxide dissolves
The temperature stops rising
The solution become neutral
Type 2:
Acid + Metal Hydroxide → Salt + Water
to obtain sodium chloride crystals given sodium hydroxide and hydrochloric acid:
HCl + NaOH → NaCl + H2O
Add 100 cm3of dilute hydrochloric acid to a beaker
Add excess mass of sodium hydroxide
When the reaction is over, filter the excess sodium hydroxide off
The filtrate is sodium chloride solution, to obtain sodium chloride powder, evaporate the solution till dryness
To obtain sodium chloride crystals, hear the solution while continuously dipping a glass rod in it
When crystals start to form on the glass rod, turn heat off and leave the mixture to cool down slowly
When the crystals are obtained, dry them between two filter papers
Observations:
Sodium hydroxide starts disappearing
Temperature rises
You know the reaction is over when:
The temperature stops rising
No more sodium hydroxide can dissolve
The pH of the solution becomes neutral
Type 3:
Acid + Metal Carbonate → Salt + Water + Carbon Dioxide
To obtain copper sulfate salt given copper carbonate and sulfuric acid:
CuCO3 + H2SO4 → CuSO4 + H2O + CO2
Add 100 cm3 of dilute sulfuric acid to a beaker
Add excess mass of copper carbonate
When the reaction is over, filter excess copper carbonate off
The filtrate is a copper sulfate solution, to obtain copper sulfate powder evaporate the solution till dryness
To obtain copper sulfate crystals, heat the solution white continuously dipping a glass rod in it
When you observe crystals starting to form on the glass rod, turn heat of and leave the mixture to cool down slowly
When you obtain the crystals dry them between two filter papers
Observations:
Bubbles of colorless gas (carbon dioxide) evolve, test by approaching lighted splint, if the CO2 is present the flame will be put off
Green Copper carbonate starts to disappear
The temperature rises
The solution turns blue
You know the reaction is finished when:
No more bubbles are evolving
The temperature stops rising
No more copper carbonate can dissolve
The pH of the solution becomes neutral Titration Method:
This is a method to make a neutralization reaction between a base and an acid producing a salt without any excess. In this method, the experiment is preformed twice, the first time is to find the amounts of reactants to use, and the second experiment is the actual one.
1st Experiment:
Add 50 cm3 of sodium hydroxide using a pipette to be accurate to flask
Add 5 drops of phenolphthalein indicator to the sodium hydroxide. The solution turns pink indicating presence of a base
Fill a burette to zero mark with hydrochloric acid
Add drops of the acid to conical flask
The pink color of the solution becomes lighter
When the solution turns colorless, stop adding the acid (End point: is the point at which every base molecule is neutralized by an acid molecule)
Record the amount of hydrochloric acid used and repeat the experiment without using the indicator
After the 2nd experiment, you will have a sodium chloride solution. Evaporate it till dryness to obtain powdered sodium chloride or crystalize it to obtain sodium chloride crystals
Preparing Insoluble Salts:
Precipitation Method:
A precipitation reaction is a reaction between two soluble salts. The products of a precipitation reaction are two other salts, one of them is soluble and one is insoluble (precipitate).
Example: To obtain barium sulfate salt given barium chloride and sodium sulfate:
BaCl2 + Na2SO4 → BaSO4 + 2NaCl
Ionic Equation: Ba2+ + SO42- → BaSO4
Add the two salt solutions in a beaker
When the reaction is over, filter and take the residue
Wash the residue with distilled water and dry it in the oven
Observations:
Temperature increases
An insoluble solid precipitate (Barium sulfate) forms
You know the reaction is over when:
The temperature stops rising
No more precipitate is being formed
Controlling Soil pH:
If the pH of the soil goes below or above 7, it has to be neutralized using an acid or a base. If the pH of the soil goes below 7, calcium carbonate (lime stone) is used to neutralize it. The pH of the soil can be measured by taking a sample from the soil, crushing it, dissolving in water then measuring the pH of the solution.
Colors of Salts:Salt Formula Solid In Solution
Hydrated copper sulfate CuSO4.5H2O Blue crystals Blue
Anhydrous copper sulfate CuSO4 White powder Blue
Copper nitrate Cu(NO3)2 Blue crystals Blue
Copper chloride CuCl2 Green Green
Copper carbonate CuCO3 Green Insoluble
Copper oxide CuO Black Insoluble
Iron(II) salts E.g.: FeSO4, Fe(NO3)2 Pale green crystals Pale green
Iron(III) salts E.g.: Fe(NO3)3 Reddish brown Reddish brown
Tests for Gases:Gas Formula Tests
Ammonia NH3 Turns damp red litmus paper blue
Carbon dioxide CO2 Turns limewater milky
Oxygen O2 Relights a glowing splint
Hydrogen H2 ‘Pops’ with a lighted splint
Chlorine Cl2 Bleaches damp litmus paper
Nitrogen dioxide NO2 Turns damp blue litmus paper red
Sulfur dioxide SO2 Turns acidified aqueous potassium dichromate(VI) from orange to green
Tests for Anions:Anion Test Result
Carbonate (CO32-) Add dilute acid Effervescence,
carbon dioxide produced
Chloride (Cl-)
(in solution) Acidify with dilute nitric acid, then add
aqueous silver nitrate White ppt.
Iodide (I-)
(in solution) Acidify with dilute nitric acid, then add
aqueous silver nitrate Yellow ppt.
Nitrate (NO3-)
(in solution) Add aqueous sodium hydroxide, then
aluminium foil; warm carefully Ammonia produced
Sulfate (SO42-) Acidify, then add aqueous barium nitrate White ppt.
Tests for aqueous cations:Cation Effect of aqueous sodium hydroxide Effect of aqueous ammonia
Aluminium (Al3+) White ppt., soluble in excess giving a
colourless solution White ppt., insoluble in excess
Ammonium (NH4+) Ammonia produced on warming –
Calcium (Ca2+) White ppt., insoluble in excess No ppt. or very slight white ppt.
Copper (Cu2+) Light blue ppt., insoluble in excess Light blue ppt., soluble in excess,
giving a dark blue solution
Iron(II) (Fe2+) Green ppt., insoluble in excess Green ppt., insoluble in excess
Iron(III) (Fe3+) Red-brown ppt., insoluble in excess Red-brown ppt., insoluble in excess
Zinc (Zn2+) White ppt., soluble in excess,
giving a colourless solution White ppt., soluble in excess,
giving a colourless solution
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