# Describe the process of catalytic cracking and explain why cracking is a necessary industrial process.

> AQA A-Level Chemistry (7405) — 3.3.15 NMR spectroscopy (A-Level only) · Describe and Explain · 5 marks

## Mark scheme (5 marks)

1. Long-chain hydrocarbons are heated to vaporise / turn them into a gas
2. The vapour is passed over a hot powdered aluminium oxide catalyst
3. The long-chain molecules split apart / break down into smaller molecules on the surface of the catalyst
4. There is greater demand for shorter-chain fractions (e.g. petrol / fuels) than for longer-chain fractions, so cracking converts less useful long-chain hydrocarbons into more useful shorter-chain ones
5. Cracking also produces alkenes, which can be used as monomers to make polymers / to produce other useful chemicals

## Key terms

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

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-process-of-catalytic-cracking-2cc5c4b7) · Published by Druglandscape Ltd.