Ethyl ethanoate is an ester that can be produced in a laboratory. Explain how ethyl ethanoate could be made from ethanoic acid, including the conditions needed and how a pure sample could be separated from the reaction mixture.

WJEC A-Level Chemistry (Wales) — 4.5 Carboxylic acids and their derivatives · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

1. Ethanoic acid reacts with ethanol to give ethyl ethanoate and water.
2. A strong acid catalyst, e.g. concentrated sulphuric acid, is added.
3. The mixture is heated to drive the equilibrium toward ester formation and to increase the rate.
4. Water is produced as a by‑product of the esterification.
5. The ester is separated by fractional distillation, exploiting its lower boiling point compared with the acid and water.

Examiner tips

  • Use the word ‘reacts’ and mention the acid catalyst; include heating and water formation; state distillation and the reason (lower boiling point).
  • Show the reaction equation if space allows.

Common mistakes

  • Omitting the acid catalyst or the water by‑product; confusing the order of addition; using evaporation instead of distillation for separation.

Mark scheme (5 marks)

  1. Ethanoic acid is reacted with ethanol (to form the ester)
  2. An acid catalyst is required / concentrated sulfuric acid is used as a catalyst
  3. The mixture is heated (to speed up the reaction / increase the yield in a reasonable time)
  4. Water is also produced in the reaction (esterification produces water as a by-product)
  5. The ester can be separated from the mixture by distillation (as it has a lower boiling point than the other components / it evaporates first)

Key terms in this question

ester

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