Ethanol can be produced by two different methods: fermentation of glucose and the hydration of ethene. Compare these two methods of producing ethanol in terms of the conditions required and the type of process used.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
Fermentation uses yeast (enzymes) as a catalyst, whereas hydration of ethene uses a phosphoric acid catalyst.
Fermentation is carried out at a low to moderate temperature (≈25–37 °C), while the hydration of ethene requires a high temperature.
Fermentation is performed at normal or atmospheric pressure, whereas the hydration of ethene is carried out at high pressure.
Fermentation is a batch process, in contrast to the continuous process used for the hydration of ethene.
Fermentation uses a renewable resource (glucose, sugar or biomass), whereas the hydration of ethene uses a non‑renewable resource (ethene derived from crude oil or fossil fuels).
Fermentation is carried out at a low to moderate temperature (≈25–37 °C), while the hydration of ethene requires a high temperature.
Fermentation is performed at normal or atmospheric pressure, whereas the hydration of ethene is carried out at high pressure.
Fermentation is a batch process, in contrast to the continuous process used for the hydration of ethene.
Fermentation uses a renewable resource (glucose, sugar or biomass), whereas the hydration of ethene uses a non‑renewable resource (ethene derived from crude oil or fossil fuels).
Examiner tips
- Use the exact terminology (yeast/enzymes, phosphoric acid, batch/continuous, renewable/non‑renewable).
- Show the key differences in order: catalyst, temperature, pressure, process type, resource type.
Mark scheme (5 marks)
- Fermentation uses yeast / enzymes (as a catalyst) whereas hydration of ethene uses a catalyst of phosphoric acid
- Fermentation occurs at a low/moderate temperature (around 25–37 °C) whereas hydration of ethene requires a high temperature
- Fermentation occurs at normal/atmospheric pressure whereas hydration of ethene requires high pressure
- Fermentation is a batch process whereas hydration of ethene is a continuous process
- Fermentation uses a renewable resource (glucose/sugar/biomass) whereas hydration of ethene uses a non-renewable resource (ethene/crude oil/fossil fuels)
Key terms in this question
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