# Crude oil contains hydrocarbons with sulfur impurities. Explain why the incomplete combustion of these hydrocarbons in a car engine is harmful to human health and to the environment.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 4.1 Introduction · Explain · 4 marks

## Mark scheme (4 marks)

1. Incomplete combustion occurs when there is insufficient oxygen
2. Carbon monoxide is produced, which is toxic / harmful to humans
3. Carbon particulates are produced, which cause health problems / global dimming
4. Sulfur impurities burn to produce sulfur dioxide, which reacts with water vapour to form acid rain

## Key terms

- [incomplete combustion](https://www.gradenine.co.uk/glossary/incomplete-combustion)
- [sulfur impurities](https://www.gradenine.co.uk/glossary/sulfur-impurities)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](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/crude-oil-contains-hydrocarbons-with-sulfur-12f3a908) · Published by Druglandscape Ltd.