# Chloroethane can be made by reacting ethane with chlorine in the presence of ultraviolet light. Describe what happens during this reaction and explain why the product is classified as a halogenoalkane.

> AQA A-Level Chemistry (7405) — 3.3.3 Halogenoalkanes · Describe and Explain · 5 marks

> Ethane reacts with chlorine in the presence of ultraviolet light to form chloroethane and hydrogen chloride: C₂H₆ + Cl₂ → C₂H₅Cl + HCl

## Mark scheme (5 marks)

1. Ultraviolet light provides the energy needed to initiate / start the reaction
2. A hydrogen atom in ethane is substituted / replaced by a chlorine atom
3. Hydrogen chloride (HCl) is also produced as a by-product
4. A halogenoalkane contains a halogen atom bonded to an alkane / carbon chain
5. Chloroethane is a halogenoalkane because it contains a chlorine atom (a halogen) bonded to an ethane / alkane carbon chain

## Key terms

- [halogenoalkane](https://www.gradenine.co.uk/glossary/halogenoalkane)
- [ultraviolet light](https://www.gradenine.co.uk/glossary/ultraviolet-light)
- [halogen](https://www.gradenine.co.uk/glossary/halogen)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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