# A student tests two hydrocarbon samples, X and Y, with bromine water. Sample X decolourises the bromine water from orange to colourless. Sample Y has no effect on the bromine water. Explain what these results show about the structure and bonding of samples X and Y, and state one use for each type of hydrocarbon.

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

## Mark scheme (5 marks)

1. Sample X is an alkene (unsaturated hydrocarbon)
2. Sample X has a carbon-carbon double bond, which makes it reactive enough to decolourise bromine water
3. Sample Y is an alkane (saturated hydrocarbon) / has only single bonds between carbon atoms
4. A correct use for an alkene — e.g. making polymers / as a monomer for addition polymerisation
5. A correct use for an alkane — e.g. as a fuel (petrol / diesel / kerosene / LPG)

## Key terms

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

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "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/a-student-tests-two-hydrocarbon-samples-3995bbc8) · Published by Druglandscape Ltd.