# Ethene can be produced by cracking long-chain hydrocarbons from crude oil. Describe the two methods by which cracking can be carried out, and explain why cracking is a useful industrial process.

> AQA A-Level Chemistry (7405) — 3.3.8 Aldehydes and ketones (A-Level only) · Describe · 5 marks

## Mark scheme (5 marks)

1. Catalytic cracking: long-chain hydrocarbons are heated to vaporise them and the vapour is passed over a hot powdered aluminium oxide catalyst
2. Steam cracking: long-chain hydrocarbons are vaporised, mixed with steam and heated to a very high temperature
3. Cracking breaks down larger/longer-chain hydrocarbons into smaller/shorter-chain molecules
4. Shorter-chain hydrocarbons / products are more flammable, making them more useful as fuels
5. Cracking also produces alkenes (e.g. ethene), which can be used to make polymers / other chemicals

## Key terms

- [cracking](https://www.gradenine.co.uk/glossary/cracking)
- [hydrocarbons](https://www.gradenine.co.uk/glossary/hydrocarbons)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/ethene-can-be-produced-by-cracking-2a24a13a) · Published by Druglandscape Ltd.