Organic chemistry

Question 1

what is ethanol

Answer 1

the alcohol in beer, wine and other alcoholic drinks. different drinks contain different amounts of alcohol. e.g. beer is usually 4-6% and vodka 40%

Question 2

how is ethanol produced. give the word equation

Answer 2

produced from carbohydrates by a process called fermentation. carbon dioxide is also produced in the reaction. carbohydrates can be sugars from fruit, such as grapes. yeast is a fungus. it provides enzymes needed for fermentation to happen.

sugar > ethanol + carbon dioxide
C6H120G(aq) > 2C2H5OH(aq) + 2CO2

Question 3

explain why fermentation mixture must be kept warm and under anaerobic conditions

Answer 3

reaction is too slow at low temp and yeast enzymes dont work at high temp. fermentation is a type of anaerobic respiration. if oxygen is present, aerobic respiration happens instead, producing carbon dioxide and water

Question 4

what are the effects of alcohol

Answer 4

increased reaction times, loss of coordination, vomiting. long term = liver cirrhosis and can damage the heart

Question 5

why is fractional distillation needed

Answer 5

to obtain more concentrated solutions of ethanol

Question 6

how can you make ethanol from ethene

Answer 6

by reacting ethene with steam in the presence of a catalyst. this is a hydration reaction (water is added). the ethene needed is made by cracking crude oil

Question 7

how can you make ethene from ethanol

Answer 7

by heating ethanol to high temperatures in the presence of a catalyst. this is a example of dehydration

Question 8

what are the pros and cons of fermentation

Answer 8

1) fermentation uses a renewable resource

2) quality of ethanol isn’t good, expensive to concentrate and purify ethanol

Question 9

what is a homologous series

Answer 9

series of compounds that:
> have same general formula
> show a gradual trend in physical properties
> have similar chemical propetrties

Question 10

how can you tell if a substance is a alkane or alkene or a alcohol

Answer 10

alkenes de-colourise orange-brown bromine water but alkanes and alcohols cannot do this

Question 11

describe a alkane, structure and features

Answer 11

ends in ane, single bonds, CnH2n+2, saturated, flammable, form carbon dioxide and water when they burn completely

Question 12

describe a alkene, structure and features

Answer 12

ends in ene, has a double bond, Cn2n, flammable

Question 13

describe a alcohol, structure and features

Answer 13

ends in ol, has a hydroxol group, CnH2n+1OH, burn with clean blue flame.

Question 14

how can you form ethanoic acid. how can you use this

Answer 14

by oxidising ethanol. can use this in the manufacture of vinegar

Question 15

what do you get when you oxidise ethanol

Answer 15

ethanoic acid

Question 16

what is vinegar, describe its uses

Answer 16

vinegar contains dilute ethanoic acid. used as a flavouring and a preservative because bacteria cannot survive in the acidic environment

Question 17

describe the structure and features of carboxylic acids

Answer 17

CnH2n+1COOH

Question 18

how is a ester produced

Answer 18

the reaction between an alcohol and a carboxylic acid produces an ester and water.

Question 19

give features of a ester

Answer 19

have pleasant, often fruity smells

Question 20

give 2 uses of esters

Answer 20

used perfumes and as food flavourings because they have pleasant smells

Question 21

what are polyesters

Answer 21

polymers made from two types of monomer. one type of monomer has a carboxyl group at each end and the other has a hydroxyl group at each end. the two types react together, making polymer molecules containing many ester bonds.

Question 22

give uses of polyesters

Answer 22

can be made into long thin fibres. these can be woven together to make fabrics. polyesters are also used to make drinks bottles. these can be recycled to make fleece, which is used to make clothing.

Question 23

how do you make ethyl ethanoate, give the word equation and symbol equation

Answer 23

from ethanoic acid and ethanol:
ethanoic acid + ethanol > ethyl ethanoate + water
CH3COOH + C2H5OH > CH3COOC2H5 + H2O

Question 24

describe the process of making soaps.

Answer 24

made by boiling oils or fats with a concentrated alkali solution. the esters break down to form:
> an alcohol called glycerol
> sodium salts or potassium salts of carboxylic acids with long carbon chains.
these salts are soaps

Question 25

what are oils and fats

Answer 25

esters

Question 26

Describe the breaking down of oils and fats

Answer 26

the esters break down to form:
> an alcohol called glycerol
> sodium salts or potassium salts of carboxylic acids with long carbon chains.
these salts are soaps

Question 27

how does a soap removes dirt or grease

Answer 27

1) hydrophobic tails dissolve in the grease and the hydrophilic heads dissolve in the water
2) some of the soap anions get beneath the grease and start to lift it off the surface
3) grease leaves the fabric, surrounded by soap anions

Question 28

how can liquid oils can be converted to solid fats

Answer 28

oils can be converted into fats for use in margarine catalytic hydrogenation. the oils are reacted with hydrogen gas in the presence of a catalyst. this converts carbon-carbon double bonds in the oils into single bonds

Question 29

what are the pros and cons of reacting ethene with steam to produce ethanol

Answer 29

1) relatively cheap
2) can be made continuously and quickly, product is high quality
3) produced from crude oil, non renewable. will become expensive in future