Propanoic acid reacts with methanol to form an ester. Describe the type of reaction that occurs, name the ester produced, identify the functional group present in the ester, and explain one use of esters.

AQA A-Level Chemistry (7405) — 3.3.9 Carboxylic acids and derivatives (A-Level only) · Describe · 5 marks · View as Markdown

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

Model answer (5 marks)

The reaction is a condensation reaction that produces water as a small molecule.
The ester formed is methyl propanoate.
The functional group present in the ester is the ester linkage –COO–.
One use of esters is as flavourings in food and drinks.

Examiner tips

  • Use the word "condensation" and mention water. State the exact ester name. Identify the ester functional group. Give a valid single use of esters.

Common mistakes

  • Calling the reaction a substitution instead of condensation. Giving the wrong ester name (e.g. propyl propanoate). Failing to mention the ester functional group. Listing an invalid use of esters.

Mark scheme (5 marks)

  1. The reaction is a condensation reaction
  2. Water is produced / lost as a small molecule during the reaction
  3. The ester produced is methyl propanoate
  4. The functional group present in the ester is –COO– / the ester linkage / ester functional group
  5. Esters are used as flavourings / perfumes / solvents (any one valid use)

Key terms in this question

ester · functional group

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