A Levels Chemistry (9701)•9701/12/M/J/22
Explanation
Esterification Stoichiometry for Ethyl Butanoate
Steps:
- Molar mass of ethyl butanoate (C₆H₁₂O₂) is 116 g/mol; moles from 2.32 g = 2.32 / 116 = 0.02 mol.
- Esterification: 1 mol acid + 1 mol alcohol → 1 mol ester + 1 mol water.
- Moles of water produced = 0.02 mol.
- Mass of water = 0.02 mol × 18 g/mol = 0.36 g.
Why A is correct:
- Row A identifies ethanol and butanoic acid, yielding 0.36 g water per the 1:1 molar ratio in esterification.
Why the others are wrong:
- B: 0.40 g mismatches calculated 0.36 g from stoichiometry.
- C: 0.36 g correct mass but wrong alcohol/acid pair for ethyl butanoate.
- D: 0.40 g mismatches calculated 0.36 g from stoichiometry.
Final answer: A
Topic: Carboxylic acids and derivatives
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