# Benzene, C₆H₆, is an aromatic hydrocarbon. A student claims that benzene should react readily with bromine water because it contains carbon-carbon double bonds. Evaluate this claim, referring to the structure and stability of benzene in your answer.

> WJEC A-Level Chemistry (Wales) — 4.2 Aromaticity · Evaluate · 5 marks

## Mark scheme (5 marks)

1. The student's claim is incorrect / benzene does not readily react with bromine water (does not decolourise bromine water)
2. Benzene does not contain localised carbon-carbon double bonds; the electrons are delocalised / spread around the ring
3. All carbon-carbon bonds in benzene are equal / intermediate in length between a single and a double bond
4. The delocalisation makes benzene more stable than expected / gives benzene extra stability (delocalisation / aromatic stabilisation energy)
5. Because disrupting the delocalised system requires a lot of energy, benzene undergoes substitution rather than addition (to preserve the stable aromatic ring)

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Evaluate" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/benzene-c-h-is-an-aromatic-hydrocarbon-16d817d6) · Published by Druglandscape Ltd.