Comparing the two methods of producing ethanol

3 marks · Normal

Ethanol is used as a fuel in some countries and can be produced either by fermentation or by hydration of ethene.

Explain, using your knowledge of resources and processing, why some countries may switch from hydration of ethene to fermentation to produce ethanol in the future.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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Also accept: Explanation should mention that oil (for ethene) is finite, may run out, whereas fermentation uses renewable plants/crops that can be regrown. May refer to sustainability, environmental benefit, or need to replace oil as a raw material.

Common mistakes: Only stating one factor, e.g., cost, without reference to resources, or missing the renewable/fossil distinction.

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Marking points

M1 · 1 mark · Mentions that hydration uses non-renewable, petroleum-based ethene/oil.

M2 · 1 mark · States that oil is finite and may run out in the future.

A1 · 1 mark · Explains that fermentation uses renewable resources like plants and is a sustainable alternative.

Worked solution

Hydration of ethene depends on crude oil, which is a finite, non-renewable resource. In the future, if oil supplies run out, it will not be possible to continue using this method. Fermentation, however, uses renewable resources like sugar cane or corn. These can be grown again each year, making fermentation a sustainable option for ethanol production when oil supplies are depleted.