Comparing the two methods of producing ethanol
3 marks · EasyCountries without access to oil often use fermentation to produce ethanol.
State one reason why some countries choose fermentation over hydration of ethene.
Describe one condition needed during fermentation.
Give one disadvantage of ethanol produced by fermentation.
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(a) Fermentation uses renewable or locally available resources (e.g. sugar cane or starch crops).
(b) Must be carried out in the absence of air (anaerobic conditions) / temperature between 30 and 40°C / yeast required.
(c) Ethanol from fermentation is impure and needs further processing, or process is slow.
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Marking points
B1a (a) · 1 mark · Gives a valid reason for using fermentation (e.g. local, renewable raw materials).
B1b (b) · 1 mark · Describes one correct fermentation condition (e.g. absence of air, specific temperature, yeast used).
B1c (c) · 1 mark · States one disadvantage of fermentation ethanol (e.g. impure, requires further processing, slow).
Worked solution
(a) Fermentation uses crops that grow locally, rather than oil.
(b) Fermentation needs to be done without air present, often with yeast, at 30-40°C.
(c) The ethanol produced is impure and needs more processing.