How does a catalyst work?
2 marks · NormalExplain, with reference to activation energy, how a catalyst affects a reaction profile diagram.
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A catalyst provides an alternative reaction pathway with a lower activation energy, shown on a reaction profile diagram as a smaller peak compared to the uncatalysed reaction.
Also accept: A catalyst offers a different route for the reaction which requires less activation energy so the curve's peak on the reaction profile diagram is lower.; The catalyst allows the reaction to occur via a pathway with lower activation energy, which is shown as a lower hump on the reaction profile diagram.
Common mistakes: Saying the catalyst lowers activation energy itself rather than providing an alternative pathway.; Not mentioning the diagram.
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Marking points
B1 · 1 mark · Mentions that a catalyst provides an alternative route/pathway (or method) for the reaction.
B2 · 1 mark · States that this route/pathway has lower activation energy (shown on the reaction profile as a lower peak/hump).
Worked solution
A catalyst provides an alternative pathway for the reaction that has a lower activation energy. On a reaction profile diagram, this is seen as a lower peak compared to the reaction without a catalyst.