# Explain why shorter-chain alkane fractions obtained from crude oil are more useful as fuels than longer-chain alkane fractions.

> Edexcel GCSE Chemistry (1CH0) — 10.1 Crude oil, hydrocarbons and alkanes (Chem only) · Explain · 4 marks

> Crude oil is a mixture of hydrocarbon molecules of different chain lengths. After fractional distillation, refineries often have a surplus of longer-chain fractions and a greater demand for shorter-chain fractions.

## Mark scheme (4 marks)

1. Shorter-chain alkanes have lower boiling points / are more volatile
2. Shorter-chain alkanes ignite / burn more easily (are more flammable)
3. Shorter-chain alkanes have lower viscosity / flow more easily / are less viscous
4. These properties make shorter-chain alkanes more practical / easier to use as fuels (e.g. in engines or combustion systems)

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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/explain-why-shorter-chain-alkane-fractions-obtained-7a7b836b) · Published by Druglandscape Ltd.