CAIE A Level Chemistry 9701 · Reaction kinetics
Catalysts can be classified as homogeneous or heterogeneous. Iron is used as a heterogeneous catalyst in the Haber process for the production of ammonia. Oxides of nitrogen act as homogeneous catalysts in the atmospheric oxidation of sulfur dioxide. Explain the mode of action of each type of catalyst, referring to the examples given.
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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