CAIE A Level Chemistry 9701 · Reaction kinetics
In a catalytic converter, oxides of nitrogen such as NO are removed from exhaust gases by reaction with carbon monoxide over a platinum catalyst. Explain, in terms of adsorption, bond weakening and desorption, how the platinum catalyst allows this reaction to occur.
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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.