Catalysts in industry
2 marks · HardDescribe two key features that should be shown on a reaction profile diagram to illustrate the effect of a catalyst on a reaction.
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Also accept: Both the uncatalysed and catalysed activation energies should be shown and labelled.; The difference in height between reactants and products (ΔH) must be the same for both paths.; Catalysed path (peak) is lower than uncatalysed path, showing reduced activation energy.
Common mistakes: Omitting labels for activation energy.; Not mentioning comparison of both paths.; Describing only ΔH, not activation energy.
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Marking points
B1 · 1 mark · Describes that reaction profile must show both activation energies (with and without catalyst), with the catalysed path lower.
B2 · 1 mark · States that the energy difference between reactants and products (enthalpy change, ΔH) remains the same for both catalysed and uncatalysed paths.
Worked solution
The diagram should show and label both the activation energy without a catalyst and the (lower) activation energy with a catalyst. It must also show that the energy difference between reactants and products (ΔH) remains the same.