Catalysts in industry
2 marks · EasyDraw a reaction profile diagram for a reaction. Your diagram should show both the activation energy for the uncatalysed and catalysed reaction paths. Clearly label the energy of reactants, energy of products, activation energy for both paths, and the effect of the catalyst.
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Must show: x-axis labelled 'Reaction pathway', y-axis labelled 'Energy', Curve for uncatalysed path with higher peak (activation energy without catalyst), Curve for catalysed path with lower peak (activation energy with catalyst), Reactants and products at different energy levels, matched for both curves, Label for activation energy (Ea) for both paths, ΔH (enthalpy change) labelled between reactants and products
Also accept: Alternative placements for activation energy labels accepted if clearly indicated; Alternative curve style accepted if energy difference and both peaks are clear
Common mistakes: Mixing up energy levels of reactants and products; Forgetting to label both activation energies; Not showing both reaction paths
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Marking points
M1 · 1 mark · Both reaction profiles drawn (with and without catalyst), showing correct energy transition and relative heights (catalysed path has lower peak), axes labelled.
A1 · 1 mark · All required labels: activation energies for both paths, reactants and products energies, and enthalpy change (ΔH).
Worked solution
The diagram shows energy on the y-axis and reaction pathway on the x-axis. The uncatalysed reaction path is a solid curve with a high peak; the catalysed path is a dashed curve with a lower peak. Both paths start at the reactants' energy and finish at the products' energy, so ΔH is the same. Loser activation energy with the catalyst is clearly labelled.