Ethanoic acid reacts with ethanol to form an ester. Describe what type of reaction this is, name the ester produced, and explain two properties of carboxylic acids that show they behave as acids.

AQA A-Level Chemistry (7405) — 3.3.11 Amines (A-Level only) · Describe · 5 marks · View as Markdown

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

Ethanoic acid is the second member of the homologous series of carboxylic acids. It reacts with ethanol in the presence of an acid catalyst.

Model answer (5 marks)

The reaction is a condensation (esterification) reaction.
The ester formed is ethyl ethanoate.
Two properties showing carboxylic acids behave as acids are: 1) they react with metal carbonates to give CO₂ gas (effervescence); 2) they dissolve in water to give an acidic solution (pH < 7) because they are weak acids and only partially dissociate.

Examiner tips

  • Use the term "condensation (esterification) reaction" to gain the reaction type mark.
  • State the ester name exactly as "ethyl ethanoate".
  • Mention both acid properties: reaction with carbonates and aqueous dissociation to give pH < 7.

Mark scheme (5 marks)

  1. The reaction between ethanoic acid and ethanol is a condensation reaction
  2. The ester produced is ethyl ethanoate
  3. Carboxylic acids react with carbonates / metal carbonates to produce carbon dioxide (gas / effervescence)
  4. Carboxylic acids dissolve in water to produce an acidic solution / solution with pH less than 7
  5. Carboxylic acids are weak acids / only partially dissociate in water (compared to strong acids such as hydrochloric acid)

Key terms in this question

ester · carboxylic acid

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