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Ethanol can be used as a fuel for cars. Pure ethanol (100%) can be used in specially adapted car engines. Petrol with up to 10% ethanol can be used in ordinary car engines. To mix with petrol the ethanol must not contain any water. Ethanol can be made from plants or from crude oil.
fermentation distillation dehydration
plants → sugars → 15% ethanol in water → 96% ethanol → 100% ethanol
distillation cracking catalyst + steam
crude oil → fractions → ethene → 100% ethanol
a Suggest one environmental advantage of making ethanol fuel from plants rather than from crude oil.
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b Suggest one economic disadvantage of producing ethanol fuel from plants rather than from crude oil.
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c Suggest one environmental disadvantage of producing ethanol fuel from plants.
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d 10% ethanol in petrol can be used in ordinary car engines. Suggest one other advantage of using 10% ethanol in petrol as a fuel rather than pure ethanol.
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