Ethanol is a member of the alcohols homologous series and has many uses as a fuel and solvent. State the functional group present in all alcohols and describe TWO ways in which ethanol can be produced.

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

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

Model answer (4 marks)

The functional group present in all alcohols is the hydroxyl group –OH.

Ethanol can be produced in two ways:
1. Fermentation of a sugar solution using yeast, which converts sugars to ethanol anaerobically.
2. Hydration of ethene (C₂H₄) with steam in the presence of a phosphoric acid catalyst to give ethanol.

Examiner tips

  • Use the exact term ‘hydroxyl group –OH’ for full marks. Mention ‘fermentation of a sugar solution using yeast’ and ‘hydration of ethene with steam, catalysed by phosphoric acid’ to cover both methods.
  • Include the word ‘anaerobically’ for fermentation and ‘phosphoric acid catalyst’ for hydration to show full understanding.

Common mistakes

  • Writing ‘–OH group’ without specifying ‘hydroxyl’. Forgetting to state that fermentation is anaerobic or that a phosphoric acid catalyst is used in the hydration reaction. Using ‘alcohol’ instead of ‘hydroxyl group’ for the functional group.

Mark scheme (4 marks)

  1. The functional group present in all alcohols is –OH (hydroxyl group)
  2. First method of production: fermentation of sugar solutions using yeast (produces ethanol anaerobically)
  3. Second method of production: reaction of ethene with steam (hydration of ethene)
  4. A phosphoric acid catalyst is used in the reaction of ethene with steam

Key terms in this question

functional group · homologous series · alcohols

Related

More Alcohols questions

▶ Try answering this question with AI marking (free) →