# Ethanol can be produced by fermentation of sugar solutions using yeast. Ethanol can also be produced by the hydration of ethene. Explain why ethene is needed as a starting material for the hydration reaction, and describe how ethene is obtained industrially from crude oil fractions.

> AQA A-Level Chemistry (7405) — 3.3.10 Aromatic chemistry (A-Level only) · Explain · 5 marks

> Ethene is an important feedstock for the petrochemical industry. It is produced on a large scale from crude oil.

## Mark scheme (5 marks)

1. Ethene is an alkene / contains a carbon–carbon double bond / is unsaturated
2. Ethene is produced by cracking (long-chain hydrocarbons / larger alkanes)
3. The hydrocarbons are heated to vaporise them
4. Vapour is passed over a hot powdered aluminium oxide catalyst (catalytic cracking) OR mixed with steam and heated to a very high temperature (steam cracking)
5. Cracking produces smaller / shorter-chain molecules including alkenes (such as ethene)

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