# Propene is an alkene produced by cracking. Describe how propene could be identified using a chemical test, and explain why propene reacts in this way but propane does not. In your answer, refer to the bonding in both molecules.

> AQA A-Level Chemistry (7405) — 3.3.4 Alkenes · Describe and Explain · 5 marks

## Mark scheme (5 marks)

1. Add bromine water to each substance / test with bromine water
2. Propene decolourises / turns bromine water from orange to colourless
3. Propane does not decolourise / has no effect on bromine water (remains orange)
4. Propene is unsaturated / has a carbon–carbon double bond
5. Propane is saturated / only has single bonds, so cannot react with bromine water / the double bond in propene makes it more reactive than propane

## Key terms

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

## 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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/propene-is-an-alkene-produced-by-a26ee094) · Published by Druglandscape Ltd.