# Bromine water is added to a solution of potassium iodide. Describe what is observed and explain, in terms of reactivity and electron transfer, why this reaction occurs.

> Edexcel GCSE Chemistry (1CH0) — 6.2 Group 7 · Explain · 4 marks

## Mark scheme (4 marks)

1. The solution turns darker / orange-brown to dark brown (or iodine is seen to form)
2. Bromine displaces iodide ions because bromine is more reactive than iodine
3. Bromine gains electrons / is reduced (bromine molecules accept electrons from iodide ions)
4. Iodide ions lose electrons / are oxidised (iodide ions donate electrons to form iodine molecules)

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