Ethanol can be made either by fermentation or by the catalytic hydration of ethene. Table 4.1 compares some features of the two methods. Table 4.1 Feature F...
Question 1 Report
Ethanol can be made either by fermentation or by the catalytic hydration of ethene. Table 4.1 compares some features of the two methods.
| Feature | Fermentation | Catalytic hydration |
|---|---|---|
| Raw material | sugar (from plants) | ethene |
| Temperature | about 30 °C | about 300 °C |
| Rate of reaction | slow | fast |
| Type of process | batch | continuous |
| Purity of ethanol | impure / dilute | pure |
(a) State the raw material used to make ethanol in (i) fermentation and (ii) catalytic hydration. [2]
(b) State whether each of the two processes is a batch process or a continuous process. [2]
(c) Give one advantage that catalytic hydration has over fermentation. [1]
(d) Give one advantage that fermentation has over catalytic hydration. [1]
(e) Explain, in terms of resources, why fermentation is likely to become more important in the future. [2]
(f) State one everyday use of the ethanol produced by either method. [1]
Answer Details
This question tests a direct comparison of the two industrial routes to ethanol: fermentation and catalytic hydration of ethene.
(a) The raw materials are (i) sugar / glucose obtained from plants [1] and (ii) ethene, which comes from crude oil [1].
(b) Fermentation is a batch process (the vessel is filled, the reaction runs, then it is emptied and restarted) [1], whereas catalytic hydration is a continuous process (reactants flow in and product flows out without stopping) [1].
(c) An advantage of catalytic hydration (any one): it is faster, continuous, or gives a much purer product [1].
(d) An advantage of fermentation (any one): it uses a renewable raw material, needs a lower temperature, or uses less energy [1].
(e) In terms of resources, crude oil, the source of ethene, is finite and is running out [1]; whereas sugar / plant material is renewable and can be grown again each year [1]. As oil reserves fall, the renewable fermentation route becomes more important.
(f) One everyday use of ethanol (any one): as a fuel, as a solvent, or in alcoholic drinks [1].
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