# Copper carbonate decomposes when heated to form copper oxide and carbon dioxide. Explain why the total mass of products formed is always equal to the mass of copper carbonate that decomposed.

> Edexcel GCSE Chemistry (1CH0) — 1.8 Calculations involving masses · Explain · 4 marks

> A student heats a sample of copper carbonate in an open crucible and measures the mass of the solid remaining after heating. The student notices the solid mass decreases during heating.

## Mark scheme (4 marks)

1. Atoms are conserved / no atoms are created or destroyed during a chemical reaction
2. The total mass of reactants equals the total mass of products (conservation of mass)
3. Carbon dioxide is a gas that is released / escapes into the surroundings
4. The mass of copper oxide plus the mass of carbon dioxide gas released equals the original mass of copper carbonate

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
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