Catalysts in industry
3 marks · NormalThe diagram below shows the energy changes in a reaction with and without a catalyst.
The activation energy for the uncatalysed reaction is 100 kJ/mol, and the activation energy for the catalysed reaction is 60 kJ/mol. The enthalpy change (ΔH) for the reaction is -40 kJ/mol.
Calculate the difference in activation energy between the catalysed and uncatalysed routes, and explain what effect this has on the rate of reaction.
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The difference in activation energy is 40 kJ/mol. Lowering the activation energy increases the rate of reaction. kJ/mol (±0)
Must show: Calculation: 100 - 60 = 40, Correct unit, Explanation: rate increases
Also accept: Difference = 40 kJ/mol, rate is higher with catalyst
Common mistakes: Not subtracting values correctly; Incorrect units
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Subtracts correctly: 100 - 60
A1 · 1 mark · States or calculates 40 kJ/mol as the answer
E1 · 1 mark · Explains that lowering the activation energy increases the rate of reaction
Worked solution
Difference in activation energy:
Lowering the activation energy by 40 kJ/mol means more particles have the required energy to react, so the rate of reaction increases.