# Iron wool is burned in a sealed container of oxygen. After the reaction is complete, the container and its contents are reweighed. Explain what the balance reading will show and why, using the law of conservation of mass.

> Eduqas GCSE Chemistry — C3 Quantitative chemistry · Explain · 4 marks

> A student places iron wool and a sealed container of oxygen on a balance and records the starting mass. She then ignites the iron wool inside the sealed container. When the reaction is complete, she reweighs the sealed container.

## Mark scheme (4 marks)

1. The balance reading will be the same / the total mass will not change
2. The law of conservation of mass states that mass (atoms/matter) is neither created nor destroyed in a chemical reaction
3. The atoms are simply rearranged / the same atoms are present before and after (just in different substances/products)
4. The container is sealed so no atoms/matter can enter or leave, meaning the total mass cannot change

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE 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/iron-wool-is-burned-in-a-2280462a) · Published by Druglandscape Ltd.