Ethanol can be produced by two different methods: fermentation of glucose, and the hydration of ethene. Compare these two methods of producing ethanol, referring to the raw materials used and one other difference between the methods.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Fermentation uses glucose, which is a renewable raw material obtained from plants, sugar cane or other crops. Hydration of ethene uses ethene, which is derived from crude oil – a non‑renewable source.
Fermentation produces a dilute solution of ethanol that must be separated and concentrated, and it is a slow, batch process. In contrast, hydration of ethene gives pure, concentrated ethanol directly and is carried out as a continuous, faster process.
Fermentation produces a dilute solution of ethanol that must be separated and concentrated, and it is a slow, batch process. In contrast, hydration of ethene gives pure, concentrated ethanol directly and is carried out as a continuous, faster process.
Examiner tips
- Use the word ‘fermentation’ and ‘hydration of ethene’ clearly. Mention the renewable vs non‑renewable raw materials first, then give one other contrasting point (e.g. purity or process speed).
- Keep the answer concise – 4 marks, so two points per method is enough. Use correct terminology: ‘glucose’, ‘ethene’, ‘renewable’, ‘non‑renewable’, ‘dilute solution’, ‘pure ethanol’, ‘batch’, ‘continuous’.
- Avoid extra words like ‘in this answer’ or ‘the question asks’.
- Use UK spelling: ‘ethene’, ‘hydrolysis’ if needed.
Mark scheme (4 marks)
- Fermentation uses glucose (from plants/sugar cane/crops) whereas hydration of ethene uses ethene (from crude oil/a non-renewable source)
- Fermentation uses a renewable raw material whereas hydration of ethene uses a non-renewable raw material (crude oil)
- Fermentation produces a dilute solution of ethanol whereas hydration of ethene produces pure/concentrated ethanol directly
- Fermentation is a slow/batch process whereas hydration of ethene is a continuous/faster process
Key terms in this question
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