Ethanoic acid is a carboxylic acid.
(a) State what you would observe when sodium carbonate is added to ethanoic acid, and name the gas produced. [2]
(b) Ethanol reacts with propanoic acid to form an ester.
(i) Name the ester formed. [1]
(ii) Name the catalyst used. [1]
(iii) Give one use of esters. [1]
- (a) effervescence / fizzing / bubbles (allow solid dissolves / disappears if sodium carbonate is solid; reject 'gas produced' or 'carbon dioxide produced')(1)
- (a) carbon dioxide (allow CO₂)(1)
- (b)(i) ethyl propanoate(1)
- (b)(ii) (concentrated) sulfuric acid (allow H₂SO₄ / an acid catalyst)(1)
- (b)(iii) food flavourings / perfumes (allow solvents)(1)
- Answer: (a) fizzing, CO₂ (b) ethyl propanoate; conc. H₂SO₄; flavourings/perfumes
- Examiner tip: Name esters alcohol-part first ('ethyl') then acid-part ('propanoate') — 'propyl ethanoate' is a common reversal.