# Natural gas is mostly methane, a hydrocarbon. Propane is another hydrocarbon used as a fuel in camping stoves. Explain what is meant by the term 'hydrocarbon' and describe the difference in molecular structure between methane and propane, including how each molecule is represented by its molecular formula.

> OCR A-Level Chemistry A (H432) — 4.1 Basic concepts and hydrocarbons · Explain · 5 marks

> Natural gas, used in home heating, is mostly methane. Propane is used as a portable fuel in camping stoves. Both are members of the alkane homologous series.

## Mark scheme (5 marks)

1. A hydrocarbon contains hydrogen and carbon only / is a compound made of carbon and hydrogen atoms only
2. Methane has the molecular formula CH₄
3. Propane has the molecular formula C₃H₈
4. Methane has one carbon atom whereas propane has three carbon atoms
5. Both molecules contain only single covalent bonds between carbon and hydrogen (and carbon to carbon in propane) / both are alkanes with the general formula CₙH₂ₙ₊₂

## Key terms

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

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](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/natural-gas-is-mostly-methane-a-372ef967) · Published by Druglandscape Ltd.