# Halogenoalkanes can undergo hydrolysis reactions with aqueous silver nitrate solution. When 1-chloropropane, 1-bromopropane, and 1-iodopropane are each separately added to aqueous silver nitrate solution and warmed, different coloured precipitates form at different rates. Explain the differences in the rate of precipitate formation across these three halogenoalkanes, and name the colour of the precipitate formed by 1-iodopropane.

> Edexcel A-Level Chemistry (9CH0) — 6.4 Halogenoalkanes · Explain · 5 marks

> Halogenoalkanes are organic molecules in which one or more hydrogen atoms have been replaced by a halogen atom. The carbon–halogen bond is polar and can be broken during hydrolysis. The strength of the carbon–halogen bond decreases going down Group 7: C–Cl > C–Br > C–I in terms of bond strength.

## Mark scheme (5 marks)

1. The carbon–halogen bond must be broken during hydrolysis
2. The C–I bond is the weakest (or C–Cl bond is the strongest) of the three
3. 1-iodopropane reacts fastest because it has the weakest C–X bond, so it is most easily broken
4. 1-chloropropane reacts slowest because the C–Cl bond is the strongest and requires the most energy to break
5. The precipitate formed by 1-iodopropane is yellow (silver iodide)

## Key terms

- [halogenoalkane](https://www.gradenine.co.uk/glossary/halogenoalkane)
- [hydrolysis](https://www.gradenine.co.uk/glossary/hydrolysis)
- [precipitate](https://www.gradenine.co.uk/glossary/precipitate)
- [silver nitrate](https://www.gradenine.co.uk/glossary/silver-nitrate)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](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/halogenoalkanes-can-undergo-hydrolysis-reactions-with-178f0496) · Published by Druglandscape Ltd.