CAIE A Level Chemistry 9701 · Electrochemistry
Bromine water is added to a colourless aqueous solution of potassium iodide. The mixture turns brown as iodine is formed.
Suggest which species is the oxidising agent in this reaction. Justify your answer using oxidation numbers and electron transfer.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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