Carboxylic Acids

Question 1

Features of the carboxylic acid homologous series

Answer 1

Functional group is -COOH (take part in different reactions)

Names end in “anoic acid”

Question 2

General formula for Carboxylic Acids

Answer 2

CnH2n+1COOH - NOTICE THERE IS A CARBON ATOM IN THE COOH AND THEREFORE THIS NEEDS TO BE SUBTRACTED FROM THE ORIGINAL NUMBER AT THE START (IE FOR PENTANOIC ACID IT WOULD BE C4H9COOH)

Question 3

Displayed formula for carboxylic acids

Answer 3

Contains double C=O covalent bond

Question 4

How are carboxylic acids made?

Answer 4

Alcohols react with oxidise agents such as potassium manganate (VII) solution
Add some oxidising agent (potassium manganate solution - KMnO4 (aq) acidified with dilute H2SO4) to ethanol and warm IN WATER BATH
Colour change - manganate ions are purple in solution and are reduced to a very pale pink manganese when acidified potassium manganate oxidises ethanol to ethanoic acid
RISKS - wear eye protection and stir reaction carefully (can be violent) and both reactants carry hazard warnings ; ethanol is harmful and flammable and the oxidising agent is also harmful (stain hands and clothing)

Question 5

Carboxylic acids and metals

Answer 5

Salt + hydrogen

Question 6

Carboxylic acids and bases

Answer 6

Salt + water

Question 7

Carboxylic acids and carbonates

Answer 7

Salt + water + carbon dioxide

Question 8

Carboxylic acids are ———— acids

Answer 8

WEAK