# Methane is a hydrocarbon that is the main component of natural gas. When methane burns completely in oxygen, carbon dioxide and water are produced. Explain why the total mass of carbon dioxide and water produced is always equal to the total mass of methane and oxygen that reacted.

> WJEC A-Level Chemistry (Wales) — 3.2 Hydrocarbons · Explain · 5 marks

> Methane has the molecular formula CH₄. The balanced equation for the complete combustion of methane is: CH₄ + 2O₂ → CO₂ + 2H₂O

## Mark scheme (5 marks)

1. No atoms are lost or made during a chemical reaction
2. This is the law of conservation of mass
3. The same atoms are present on both sides of the equation / the atoms are rearranged to form new substances
4. Because the number of each type of atom is the same on both sides of the balanced equation
5. Therefore the mass of the products equals the mass of the reactants

## Key terms

- [hydrocarbon](https://www.gradenine.co.uk/glossary/hydrocarbon)

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/methane-is-a-hydrocarbon-that-is-ffc136e9) · Published by Druglandscape Ltd.