How does a catalyst work?
3 marks · EasyDraw and label a reaction profile diagram for an exothermic reaction, showing the energy of reactants, products, and the activation energy.
Explain how a catalyst would change the shape of this diagram.
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(a) — · must show y-axis labelled energy, x-axis labelled reaction progress, reactants higher than products, activation energy shown as peak or arrow upwards from reactants
(b) A catalyst adds a lower peak (lower activation energy) to the diagram.
Must show: energy axis, reaction progress axis, reactants and products levels (products lower), activation energy peak/arrow
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Marking points
B1 (a) · 1 mark · Reaction profile diagram: y-axis energy, x-axis reaction progress, correct shape peak then drop.
B1 (a) · 1 mark · Labels reactants, products (products lower), activation energy peak/arrow.
B1 (b) · 1 mark · Explains a catalyst gives a new lower peak (activation energy) in the diagram.
Worked solution
(b) A catalyst would add a second, lower peak, showing a lower activation energy.