# Propane (C₃H₈) is a hydrocarbon used as a fuel. When propane burns completely in oxygen, carbon dioxide and water are produced. The balanced equation for this reaction is: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. Explain why the total mass of carbon dioxide and water produced is always equal to the total mass of propane and oxygen used up.

> Eduqas A-Level Chemistry — 3.2 Hydrocarbons · Explain · 5 marks

> Propane (C₃H₈) is a hydrocarbon used as a fuel in gas-powered appliances. When propane burns completely in oxygen, the balanced equation is: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.

## Mark scheme (5 marks)

1. States the law of conservation of mass
2. No atoms are lost or made / created or destroyed during the reaction
3. The atoms are rearranged / the same atoms are present in the reactants and the products
4. Because the number of atoms of each element is the same on both sides of the equation
5. Therefore the mass of the products equals the mass of the reactants

## Key terms

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

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- [Revision notes for Eduqas A-Level Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/propane-c-h-is-a-hydrocarbon-used-15d0f985) · Published by Druglandscape Ltd.