This comparison covers Fermentation vs Hydration Comparison within Alcohols for GCSE Chemistry. Revise Alcohols in Organic Chemistry for GCSE Chemistry with 22 exam-style questions and 15 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 13 in this topic. Use this comparison to connect the idea to the wider topic before moving on to questions and flashcards.
⚖️ Fermentation vs Hydration Comparison
| Aspect | Fermentation | Hydration of Ethene |
|---|---|---|
| Raw Materials | Sugar/starch (renewable) | Ethene from crude oil (finite) |
| Temperature | 25-35°C (room temp) | 300°C (high energy) |
| Speed | Days to weeks | Continuous process |
| Purity | Low (needs distillation) | High (pure ethanol) |
| Environmental | Carbon neutral (renewable) | Uses fossil fuels |
| Scale | Batch process | Large-scale continuous |
Test yourself: fermentation vs hydration
Apply the comparison to real production decisions.
A company switches ethanol production from fermentation to hydration of ethene. Suggest one advantage and one disadvantage.3 marks
Advantage: hydration is a continuous process that runs faster and gives purer ethanol, so it is more efficient for large-scale production. Disadvantage: ethene comes from crude oil, a finite resource, and the process needs much higher temperatures (around 300°C), so it uses more energy.
One clearly explained advantage and one disadvantage, each tied to a specific factor. Vague 'it is better/worse' scores 0 for that part.
Explain why fermentation is generally considered more sustainable than hydration of ethene.2 marks
Fermentation uses sugar from plants, a renewable resource that can be replaced by growing more crops, whereas hydration uses ethene made from crude oil, a finite resource that will run out.
Sustainability answers must reference renewability of the raw material. Answers about temperature or purity alone score 0 here.
A brewery finds fermentation very slow at 15°C. Explain how the rate could be increased without killing the yeast.2 marks
Raise the temperature to the yeast's optimum of about 25-35°C, increasing the rate of the enzyme-controlled reaction. It must not go much higher, because that would denature the yeast's enzymes and stop fermentation altogether.
Full marks needs both directions — higher temperature raises rate AND there is an upper limit due to denaturation. 'Increase the temperature' alone loses the second mark.
Practice questions for Alcohols
What is the functional group present in all alcohols?
Explain what happens when ethanol reacts with sodium metal. Include a balanced equation in your answer.