# Limestone is a sedimentary rock made mainly of calcium carbonate. When limestone is heated strongly in a kiln, it undergoes thermal decomposition. Explain what happens during the thermal decomposition of calcium carbonate, naming the products formed and describing one use of each product.

> WJEC GCSE Chemistry (Wales) — 1.6 Limestone · Explain · 4 marks

## Mark scheme (4 marks)

1. Calcium carbonate breaks down / decomposes when heated
2. Calcium oxide (quicklime) is named as a product
3. Carbon dioxide is named as the other product
4. A correct use stated for either calcium oxide OR carbon dioxide

## Key terms

- [thermal decomposition](https://www.gradenine.co.uk/glossary/thermal-decomposition)
- [calcium carbonate](https://www.gradenine.co.uk/glossary/calcium-carbonate)

## Related

- [Revision notes for WJEC GCSE Chemistry (Wales)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/limestone-is-a-sedimentary-rock-made-d5ba4010) · Published by Druglandscape Ltd.