# Explain why ethene is described as an unsaturated hydrocarbon and describe a chemical test that confirms this property.

> Edexcel GCSE Chemistry (1CH0) — 10.2 Alkenes (Chem only) · Explain · 4 marks

> Ethene is a small molecule produced during the cracking of long-chain hydrocarbons. It is widely used in the polymer industry.

## Mark scheme (4 marks)

1. Ethene contains a carbon-to-carbon double bond (C=C)
2. Unsaturated means it does not contain the maximum number of hydrogen atoms / has fewer hydrogen atoms than the equivalent alkane
3. Add bromine water to ethene
4. Bromine water decolourises / turns from orange-brown to colourless, confirming the presence of a C=C bond

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-ethene-is-described-as-adad19d3) · Published by Druglandscape Ltd.