CAIE A Level Chemistry 9701 · Electrochemistry
A student electrolyses an aqueous solution of copper(II) sulfate using inert carbon electrodes. The concentration of the electrolyte is changed from 0.1 mol dm to 0.5 mol dm. Explain how the change in concentration affects which substances are liberated at each electrode.
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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