How does a catalyst work?
2 marks · HardA student says that using a catalyst lowers the energy of the reactants in a chemical reaction. Evaluate this statement. Use ideas from reaction profile diagrams in your answer.
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Also accept: The catalyst does not change the energy of the reactants. Instead, it provides an alternative reaction path with a lower activation energy, as shown on a reaction profile diagram.; The energy of reactants stays the same with a catalyst; the catalyst only affects the activation energy via an alternative pathway.
Common mistakes: Incorrectly stating that the catalyst lowers the energy of the reactants; Failing to reference reaction profile diagrams
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Marking points
B1 · 1 mark · Clearly states the catalyst does not change the energy of the reactants.
B2 · 1 mark · Explains that the catalyst only provides an alternative pathway with lower activation energy (uses or references the reaction profile diagram for support).
Worked solution
The statement is incorrect. A catalyst does not change the energy of the reactants. Instead, on a reaction profile diagram, it is shown to provide an alternative pathway with a lower activation energy, but the energy of the reactants and products stays the same.