Ethanol can be oxidised to ethanoic acid. Describe TWO different methods by which this oxidation can be carried out, and state the functional group present in ethanoic acid.

Pearson Edexcel International GCSE Chemistry (4CH1) — 4.5 Alcohols · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

1. Microbial oxidation – ethanol is oxidised by bacteria (e.g. *Acetobacter*) to acetic acid.
2. Chemical oxidation – ethanol reacts with potassium dichromate(VI) in acidic solution to give acetic acid.
The product contains the –COOH carboxyl functional group.

Examiner tips

  • Use the word ‘oxidised’ to show the change of oxidation state.
  • Mention the oxidising agent (bacteria or K₂Cr₂O₇) and the product (acetic acid).
  • State the functional group as –COOH.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Confusing the product with ethanol or mis‑labeling the functional group as –COO⁻.
  • Using the wrong oxidising agent (e.g. NaOCl) or omitting the bacteria method.

Mark scheme (4 marks)

  1. Microbial oxidation (by microorganisms/bacteria) converts ethanol to ethanoic acid
  2. Reaction with potassium dichromate(VI) converts ethanol to ethanoic acid
  3. Both methods are oxidation reactions (ethanol is oxidised in both cases)
  4. The functional group in ethanoic acid is –COOH (carboxyl group)

Key terms in this question

oxidation · functional group

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