CAIE A Level Chemistry 9701 · Group 17
A student investigates the reducing ability of halide ions. In one test, aqueous sodium chloride, sodium bromide and sodium iodide are each added to acidified silver nitrate solution. In a second test, each halide is warmed with concentrated sulfuric acid.
Explain the relative reducing ability of chloride, bromide and iodide ions, and describe what the student would observe in each test.
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.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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