CAIE A Level Chemistry 9701 · Group 17
Chlorine reacts with cold and hot aqueous sodium hydroxide to produce different products. Compare these two reactions in terms of the products formed and the changes in oxidation number of chlorine. Include balanced equations for both reactions. Then explain the role of chlorine in water purification, giving equations to show the formation of the species that kill bacteria.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.