C6.2.4

Question 1

Carboxylic acid:

Answer 1

Member of a homologous series of organic compounds containing the carboxyl group

Question 2

Carboxyl group:

Answer 2

Functional group in carboxylic acid

-COOH

Question 3

General formula for Carboxylic acids:

Answer 3

C_nH_2n+1COOH

Question 4

Chemical formula for pentanoic acid:

Answer 4

C₄H₉COOH

Question 5

How are carboxylic acids made?

Answer 5

When alcohols react with oxidising agents, such as Potassium Manganate (VII) solution

Question 6

Products of ethanol and oxidising agent:

Answer 6

Ethanoic acid and water

Question 7

Describe a test to show ethanol is oxidised to form ethanoic acid:

Answer 7

1. Use a test tube of ethanol
2. Add some oxidising agent to ethanol and warm it in a water bath

Oxidising agent:

• Potassium Manganate (VII) solution with a little dilute silfuric acid
• KMnO₄

Question 8

How can we check if ethanol has been oxidised to ethanoic acid?

Answer 8

• There is a colour change
• Manganate (VII) ions are purple in solution
• Reduced to very pale pink manganese (II) ions
• When acidified potassium manganate (VII) oxidises ethanol to ethanoic acid

Question 9

What type of acids are carboxylic acids?

Answer 9

Weak acids so their reactions are typical of acids

Question 10

What do carboxylic acids react with and what do they produce?

Answer 10

React with

• Metals to produce salts and hydrogen
• Alkalis and bases to produce salts and water
• Carbonates to produce salts, water and carbon dioxide

Question 11

What are the products when ethanoic acid reacts with sodium carbonate?

Answer 11

• Sodium Ethanoate
• Water
• Carbon Dioxide