Comparing the two methods of producing ethanol
2 marks · NormalState one advantage and one disadvantage of producing ethanol by fermentation compared to the hydration of ethene.
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Also accept: Advantage (fermentation): uses renewable resources / uses sugar, not crude oil / does not require petroleum; Disadvantage: slower process / batch process so less efficient / produces impure ethanol / needs further processing / less energy efficient
Common mistakes: Stating an advantage of hydration instead of fermentation; Giving two of the same type (both advantages or both disadvantages)
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Marking points
B1 · 1 mark · States an advantage of fermentation over hydration (e.g. uses renewable resources, does not require crude oil, etc.)
B2 · 1 mark · States a disadvantage of fermentation over hydration (e.g. slow/batch process, impure ethanol, less efficient, high labour, etc.)
Worked solution
Advantage: Fermentation uses renewable resources such as sugar cane or corn, while hydration uses non-renewable resources like crude oil.
Disadvantage: Fermentation is a slow, batch process and produces impure ethanol, whereas hydration is much faster and produces purer ethanol.