# Natural gas is mainly methane, a hydrocarbon that belongs to the alkane homologous series. Propane and butane are also alkanes used as fuels. Explain what is meant by the term 'hydrocarbon' and describe two features that all alkanes share as members of the same homologous series, including the general formula for alkanes.

> OCR A-Level Chemistry B: Salters (H433) — 4.1 Basic concepts and hydrocarbons · Explain · 5 marks

> Natural gas, bottled camping gas, and liquefied petroleum gas (LPG) all contain alkanes. These fuels combust in air to release energy, making them useful in homes and industry.

## Mark scheme (5 marks)

1. A hydrocarbon contains hydrogen and carbon only
2. All alkanes have the general formula CₙH₂ₙ₊₂
3. Alkanes differ from one another by one CH₂ unit (each successive member has one more carbon and two more hydrogen atoms)
4. All alkanes have similar chemical properties (they react in similar ways / undergo the same types of reactions)
5. All alkanes contain only single carbon–carbon bonds (they are saturated)

## Key terms

- [hydrocarbon](https://www.gradenine.co.uk/glossary/hydrocarbon)
- [alkane](https://www.gradenine.co.uk/glossary/alkane)
- [homologous series](https://www.gradenine.co.uk/glossary/homologous-series)
- [general formula](https://www.gradenine.co.uk/glossary/general-formula)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](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-mainly-methane-a-34828967) · Published by Druglandscape Ltd.