# Ethene (C₂H₄) is a hydrocarbon. A student states: 'When ethene burns completely in oxygen, the total mass of the products must equal the total mass of the reactants.' Explain why the student is correct, and state the names of the two products formed during the complete combustion of ethene.

> Eduqas A-Level Chemistry — 3.2 Hydrocarbons · Explain · 5 marks

> Ethene is a hydrocarbon gas used in the production of plastics. Like all hydrocarbons, it can undergo combustion reactions.

## Mark scheme (5 marks)

1. The student is correct because of the law of conservation of mass
2. No atoms are lost or made during a chemical reaction
3. Therefore the mass of the products equals the mass of the reactants
4. One product is carbon dioxide
5. The other product is water

## Key terms

- [complete combustion](https://www.gradenine.co.uk/glossary/complete-combustion)
- [hydrocarbon](https://www.gradenine.co.uk/glossary/hydrocarbon)
- [products](https://www.gradenine.co.uk/glossary/products)
- [reactants](https://www.gradenine.co.uk/glossary/reactants)

## Related

- [Revision notes for Eduqas A-Level Chemistry](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/ethene-c-h-is-a-hydrocarbon-a-0281afee) · Published by Druglandscape Ltd.