# When magnesium is burned in air, the mass of the product is greater than the mass of the magnesium used. Explain why the mass increases, and explain why, despite this apparent change, the law of conservation of mass still holds.

> AQA GCSE Chemistry (8462) — 4.3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations · Explain · 4 marks

## Mark scheme (4 marks)

1. Magnesium reacts with oxygen (from the air)
2. The oxygen gas has mass / the mass of oxygen is added to the mass of magnesium
3. The law of conservation of mass states that no atoms are lost or made during a chemical reaction
4. The total mass of reactants (magnesium + oxygen) equals the total mass of the product (magnesium oxide)

## Key terms

- [conservation of mass](https://www.gradenine.co.uk/glossary/conservation-of-mass)
- [product](https://www.gradenine.co.uk/glossary/product)

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](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/when-magnesium-is-burned-in-air-90b3023b) · Published by Druglandscape Ltd.