Topic 5 - Organic chemistry

Question 1

What is a homologous series?

Answer 1

Have same general formula

show a gradual increase in boiling point as it gets bigger

similar chemical properties as they contain the same functional group

each member differs from next by CH₂

Question 2

Whats the general formula for alkanes

Answer 2

C_nH_2n+2

Question 3

What is the general formula for alkenes

Answer 3

C_nH_2n

Question 4

What is the functional group of alcohol

Answer 4

OH

Question 5

How do you name alcohols?

Answer 5

same as alkanes but replace final e with oh

Question 6

What is the general formula of alcohols?

Answer 6

C_nH_2n+1OH

Question 7

What is the general formula of carboxylic acids?

Answer 7

C_nH_2n+1COOH

Question 8

How do you name carboxylic acids

Answer 8

meth/eth/prop… -anoic acid

Question 9

What is the functional group of carboxylic acids

Answer 9

-COOH

Question 10

What are the two ways to produce ethanol

Answer 10

fermentation of sugar

hydration of ethene

Question 11

How do you produce ethanol by fermetation

Answer 11

mix yeast solution of a carbohydrate (e.g. glucose) seal and leave in warm place (between 30 and 40*C) as fermentatuion happens fastest between these temperatures.

Anaerobic conditions because oxygen converts te ethanol to ethanoic acid

makes 15% alcohol

Have to purify by fractional distilation to get stronger concentration

Question 12

what is the equation of fermentation of sugar

Answer 12

glucose sugar ^yeast> ethanol + carbondioxide

C₆H₁₂O₆ -> 2C₂H₅OH + 2CO₂

Question 13

What are the advatages and disadvantages of fermentation

Answer 13

+ made from renewable source

+ biofuels

+ can be frastional distilated to get 95%

+ countries with no oil but good weather for growing crops can use it

• Need good climate to grow sugar cane
• only 15%
• expensive to concentrate and purify ethanol

Question 14

How do you produce ethanol by hydration of ethene

Answer 14

ethen made by craking crude oil fractions

will react with steam to make ethanol

high temp

catalyst used

no waste products

100%

Question 15

What is the equation of hydration of ethene

Answer 15

Ethene + steam ^{<u>Catalyst</u>}> ethanol

C₂H₄ + H₂O -> C₂H₅OH

Question 16

What are the negative effects of alcohol

Answer 16

makes people less inhibited

reduces activity of the nervous system. increased reaction times, impared judgment, poor balance and coordination, uncontious and sometimes coma

causes dehydration which can damage brain cells which can lead to noticable frop in brain function and lead to long term memory loss

Liver disease

can lead to violent behaviour

can become addicted (alcoholism) which can lead to problems with other people and losing jobs

drink driving

expensive becuase of the need of police and doctors

Question 17

what does dehydration of ethanol produce

Answer 17

ethene and water (waste product)

Ethanol -> ethene + water

C₂H₅OH -> C₂H₄ + H₂0

Question 18

What catalyst is used in dehydration of ethene

Answer 18

hot aluminium oxide

Question 19

What does hydration of ethanol produce

Answer 19

Ethanol + oxygen -> ethanoic acid + water

C₂H₅OH + O₂ -> CH₃COOH + H₂O

Question 20

What is a more common name for ethanoic acid

Answer 20

Vinegar

Question 21

What are the uses for ethanoic acid (vinegar)

Answer 21

Flavouring

preserving foods

Question 22

How do carboxylic acids react with metal

Answer 22

produce hydrogen and a salt ( metal _anoate)

Question 23

How do carboxylic acids react with bases

Answer 23

produce water and a salt (E.g sodium ethanoate)

Question 24

How do carboxylic acids react with carbonates

Answer 24

produce carbon dioxide, water, and salt (e.g sodium ethanoate)

Question 25

give the symbol of sodium ethanoate

Answer 25

CH₃COONa

Question 26

What is the functional group of esters?

Answer 26

-COO-

Question 27

How are esters fromed

Answer 27

when an alcohol reacts with a carboxylic acid.

An acid catylist is usually used (e.g concentrated sulfuric acid)

Alcohol + carboxylix acid -> ester + water

E.g ethyl ethanoate is made by reacting ethanol with ethanoic acid

Question 28

what is the displayed, strucural, and molecula formula of ethanol reacting with ethanoic acid?

Answer 28

Question 29

What are esters used in?

Answer 29

Perfumes

flavourings

fabrics (polyesters

plastics (polyesters)

Question 30

How are soaps made?

Answer 30

When an ester reacts with an alkali.

fats or oils can be boiled with concentrated alkali solution to make soap.

The oil/fat breaks down glycerol and long chain carboxylic acids and the carboxylic acids then react with the alkali

Question 31

Answer 31

A: Hydrophilic head loves water, dissolves in water (and not oil and fat). This part usually small and ionic

B: Hydrophobic tail hates water, is attracted to grease. Usually long hydrocarbon chain

Question 32

How does soap work

Answer 32

Soap anions surround the oil blob and lift it away from the fabric

Question 33

Why are vegetable oils hydrogenated for the food industry

Answer 33

Unsaturated oils are less viscous than saturated oils

Question 34

How are unsaturated oils changed into solid saturated oils

Answer 34

by breaking the double bonds and adding hydrogen.

A nickel catalyst is used. (catalytic hyddrogenation)

the oil is filtered to remove the nickel and cooled to turn it into a solid fat

Question 35

how are polyunsaturated vegatable oils used

Answer 35

hydrogenated to make margarine

not all double bonds in oil hydrogenated so some still unsaturated, firm enough to spread but lower in saturates than butter