# 1-iodopropane can react with potassium cyanide solution to form a new organic compound. State what type of reaction this is, identify the functional group that replaces the iodine atom, and explain why 1-iodopropane reacts more readily with potassium cyanide than 1-chloropропane does under the same conditions.

> Eduqas A-Level Chemistry — 2.6 Halogenoalkanes · Explain · 5 marks

> Halogenoalkanes can undergo reactions in which the halogen atom is replaced by another atom or group of atoms. The ease with which this happens depends on the strength of the carbon–halogen bond.

## Mark scheme (5 marks)

1. Names the type of reaction as substitution (nucleophilic substitution / nucleophilic substitution reaction)
2. Identifies the functional group that replaces iodine as the nitrile / cyano group (–CN)
3. States that the C–I bond is weaker than the C–Cl bond
4. States that less energy is needed to break the C–I bond
5. Concludes that the reaction of 1-iodopropane is therefore faster / more readily because the bond breaks more easily

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Source: [GradeNine](https://www.gradenine.co.uk/q/1-iodopropane-can-react-with-potassium-cyanide-d03f0121) · Published by Druglandscape Ltd.