alcohols, acids, esters, and polymers

Question 1

alcohol functional group

Answer 1

-OH

Question 2

oxidising ethanol

Answer 2

complete combustion:
- produces carbon dioxide and water

microbial oxidation:
- oxidising in the presence of microorganisms
- forms ethanoic acid

oxidation:
- heating with the oxidising agent potassium dichromate(VI) in dilute sulfuric acid
- goes from orange to green, indicating the presence of Cr³⁺ ions which are formed when the potassium dichromate(VI) is reduced

Question 3

making ethanol

Answer 3

hydration:
- ethene and steam is passed over a catalyst
- ethene is hydrated
- Catalyst: Phosphoric acid
- temperature: 300°C
- pressure: 60 atm

fermentation:
- conversion of glucose to ethanol by enzymes in yeast
- Catalyst: Zymase (enzyme found in yeast)
- temperature: 30°C, to not to denature the enzymes and to keep the reaction fast
- Anaerobic, if oxygen were present, the yeast produce carbon dioxide and water instead of ethanol

Question 4

carboxylic acids functional group

Answer 4

-COOH

Question 5

Methanoic acid: molecular and structural formula

Answer 5

Molecular formula: CH₂O₂

Structural formula: HCOOH

Question 6

Ethanoic acid: molecular and structural formula

Answer 6

Molecular formula: C₂H₄O₂

Structural formula: CH₃COOH

Question 7

Propanoic acid: molecular and structural formula

Answer 7

Molecular formula: C₃H₆O₂

Structural formula: CH₃CH₂COOH

Question 8

Butanoic acid: molecular and structural formula

Answer 8

Molecular formula: C₄H₈O₂

Structural formula: CH₃CH₂CH₂COOH

Question 9

4:36 (Triple only) describe the reactions of aqueous solutions of carboxylic acids with metals and metal carbonates

Answer 9

metals:

metal + acid -> metal …anoate + hydrogen

metal carbonates:

metal carbonate + carboxylic acid -> metal …anoate + carbon dioxide + water

Question 10

4:37 (Triple only) what is vinegar?

Answer 10

Vinegar is an aqueous solution containing ethanoic acid

Question 11

ester functional group

Answer 11

-COO-

Question 12

4:39 (Triple only) know what ethyl ethanoate is the product of

Answer 12

• Ethyl ethanoate is the ester produced when ethanol and ethanoic acid react in the presence of an acid catalyst
• ethanoic acid + ethanol -> ethyl ethanoate + water
• esterification
• condensation reaction because water is made

Question 13

know that esters are volatile compounds

Answer 13

• volatile compounds with distinctive smells.
• a volatile liquid is one that turns into to a vapour easily
• used as food flavourings and in perfumes
• often have a sweet, fruity smell
• typically smell of bananas, raspberries, pears or other fruit because esters occur in all these natural products

Question 14

4:43 (Triple only) practical: prepare a sample of an ester such as ethyl ethanoate

Answer 14

1. Heat a mixture of ethanoic acid and ethanol with a few drops of sulfuric acid
2. ethyl ethanoate is produced (ester)
3. condensation reaction because water is produced
   - reversible reaction

Question 15

4:44 know how an addition polymer is formed

Answer 15

• One bond in the double bond breaks
• Monomers join together to form a long chain
• Polymer contains only single bonds

Question 16

4:47 explain problems in the disposal of addition polymers,

Answer 16

• Polymers are inert (unreactive) as they have strong C-C bonds
• This makes them non-biodegradeable
• Biodegradable: the breakdown of a substance by microorganisms
• If burnt the addition polymers could produce toxic gases such as carbon monoxide and hydrogen chloride

Question 17

4:48 (Triple only) know what is produced in a condensation polymerisation reaction

Answer 17

• combining 2 different monomers, e.g. a dicarboxylic acids and a diol
• when these join in an alternating pattern they form a long polymer called a polyester
• water is formed, making it a condensation reaction

Question 18

what are biopolyesters

Answer 18

polyesters that break down more easily in nature