C6.2.4 - Carboxylic acids

Question 1

What is the functional group for carboxylic acids?

Answer 1

carboxyl group -COOH

Question 2

What is the general formula for carboxylic acids?

Answer 2

CnH2n+1COOH

Question 3

What is the formula for methanoic acid?

Answer 3

HCOOH

Question 4

What is the formula for ethanoic acid?

Answer 4

CH3COOH

Question 5

What is the formula for propanoic acid?

Answer 5

C2H5COOH

Question 6

What is the formula for butanoic acid?

Answer 6

C3H7COOH

Question 7

How are carboxylic acids made?

Answer 7

They are formed when alcohols react with oxidising agents, such as potassium manganite(VII) solution

Question 8

How can ethanol being oxidised to ethanoic acid be shown?

Answer 8

• Get a test tube of ethanol
• Add some oxidising agent (in this case potassium manganate solution acidified with a little dilute sulfuric acid) to the ethanol and warm it in a water bath
• The manganate(VII) ions which are purple in solution, are reduced to very pale pink manganate(II) ions when acidified potassium manganate(VII) oxidise ethanol to ethanoic acid

Question 9

What do carboxylic acids react with?

Answer 9

They react with:

• metals to produce salts and hydrogen
• alkalis and bases to produces salts and water
• carbonates to produce salts, water, carbon dioxide