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Cambridge IGCSE Chemistry · 0620
Chapter 11: Organic Chemistry — Part 6
Topic 11.6 · Alcohols
Manufacture of Ethanol
Ethanol can be manufactured by two main methods:
| Method | Conditions | Word Equation |
|---|---|---|
| Fermentation | Aqueous glucose, yeast, 25–35°C, anaerobic (no oxygen). | Glucose ? Ethanol + Carbon dioxide. |
| Catalytic Hydration | Reacting ethene with steam, phosphoric acid catalyst, 300°C, 60 atm. | Ethene + Steam ? Ethanol. |
Exam Traps
- Do not forget CO2 as a fermentation product — glucose → ethanol + carbon dioxide, not ethanol alone.
- Do not mix up catalysts: yeast for fermentation, phosphoric acid for hydration — not nickel or sulfuric acid.
Comparison of Methods
- Fermentation: Uses renewable raw materials, is inexpensive, but is slow and produces impure ethanol.
- Catalytic Hydration: Uses non-renewable ethene, is expensive and energy-intensive, but is fast and produces pure ethanol.
Exam Traps
- Do not say fermentation produces pure ethanol — the product is a dilute aqueous mixture that needs distillation.
- Do not claim fermentation is fast — it takes days; catalytic hydration runs continuously in industry.
Properties and Uses
- Combustion: Ethanol burns in oxygen (complete combustion) to produce carbon dioxide and water, releasing a lot of energy.
- Uses: Widely used as a solvent and as a fuel.
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