Organic Chemistry

Question 1

Alcohols

Answer 1

Contain the functional group –OH, all end in the suffix -ol

First 3 alcohols of the homologous series are:

1. Methanol (CH3OH)
2. Ethanol (CH3CH2OH)
3. Propanol (CH3CH2CH2OH)

Can be represented by the following display formula where each line represents a covalent bond.

Question 2

Properties & uses of methanol, ethanol and propanol

Answer 2

Dissolve in water to form a neutral solution

React with sodium to produce hydrogen
e.g
methanol + sodium → sodium ethoxide + hydrogen
2CH3OH + 2Na → 2Na(CH3O) + H2

Burn in air
e.g
methanol + oxygen → Carbon dioxide + water
2CH3OH + 3O2 → 2CO2 + 4H2O

Uses:
• Fuel
• Ethanol is used in alcoholic drinks

Question 3

Ethanol oxidation

Answer 3

Can be oxidised to produce ethanoic acid by chemical oxidation or by microbial action.

Ethanoic acid is the main acid in malt vinegar

Question 4

Carboxylic acids

Answer 4

Contain the functional group – COOH, all end in the suffix –noic acid.

Ethanoic acid is a carboxylic acid
Formula CH3COOH

Question 5

Properties of Carboxylic acid

Answer 5

Dissolve in water to produce an acidic solution

React with carbonates to produce carbon dioxide (hence will fizz)

Salts are named metal -anoate

e.g Sodium ethanoate)

React with alcohols in the presence of an acid catalyst to produce an ester.
e.g
Ethanol + Ethanoic acid → ethyl ethanoate

Question 6

Carboxylic acid – Weak acid

Answer 6

Carboxylic acid only partially ionise in solution hence they are weak acids because the carboxylic acid is in constant equilibrium.

Strong acid fully ionise as they are not in equilibrium in solution

Weak acid of the same concentration as strong acids will have a higher pH

e.g.

Ethanoic acid, 0.1 mol/dm3, pH = 5.5
Hydrochloric acid, 0.1 mol/dm3, pH = 1

Question 7

Esters

Answer 7

Contain the functional group –COO-

E.g ethyl ethanoate CH3COOCH2CH3

Made by reacting carboxylic acids with alcohols in the presence of an acid catalyst to produce an ester.
e.g
Ethanol + Ethanoic acid → ethyl ethanoate

Volatile

Have distinct smells and are used as flavourings and perfumes.