Ethanol burns in air

2 marks · Hard

Describe what would be observed if ethanol vapour is passed over heated copper(II) oxide, and state the type of reaction taking place.

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Also accept: Black copper(II) oxide turns reddish brown/copper, ethanol is oxidised to a product such as ethanal or acetic acid; Observation: black solid turns brown/reddish (coating of copper formed). Type of reaction: oxidation

Common mistakes: Only describing colour change but not stating oxidation; Saying 'combustion' instead of 'oxidation'

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Marking points

B1 · 1 mark · Observation: black copper(II) oxide turns reddish brown or copper is formed

B2 · 1 mark · Correctly states the type of reaction as oxidation (not combustion)

Worked solution

Passing ethanol vapour over heated copper(II) oxide causes the black copper(II) oxide to turn brown, as copper is formed.

This is an oxidation reaction: ethanol is oxidised.