Catalysts: Past Paper Mastery
Definitions, Collision Theory & Reaction Pathway Diagrams · 15 Questions
The Golden Rule for Catalysts
A catalyst is like a mountain guide who knows a secret tunnel through the mountain. The start (reactants) and end (products) are identical — but the route is shorter. The tunnel = lower activation energy. The guide doesn't carry your bags permanently — it's regenerated each trip.
15 questions · 33 marks available
Define the term catalyst.
What name is given to biological catalysts found in living organisms?
Manganese(IV) oxide is used as a catalyst in the decomposition of hydrogen peroxide. State what happens to the manganese(IV) oxide during and after the reaction.
The industrial production of ammonia uses iron as a catalyst. State two characteristics that define a substance as a catalyst.
Suggest why a small amount of catalyst can catalyse a very large amount of reactant.
Explain, using collision theory, how a catalyst increases the rate of a chemical reaction.
A student says: 'A catalyst works by making particles move faster and collide more often.' Explain why this statement is incorrect.
Explain the difference between a homogeneous catalyst and a heterogeneous catalyst. Give one example of each.
The decomposition of hydrogen peroxide is catalysed by manganese(IV) oxide. A student increases the mass of manganese(IV) oxide used. Predict and explain the effect on the initial rate of reaction.
Enzymes are biological catalysts. State two ways in which enzymes differ from inorganic catalysts such as iron.
[DIAGRAM] The reaction profile below shows the uncatalysed reaction between reactants X and Y. On the same diagram, sketch the reaction profile for the catalysed version of this reaction. Label the catalysed curve and mark the new activation energy (Ea cat).
Interactive: Toggle curves and labels above
[DIAGRAM] On the reaction profile, draw and label the activation energy (Ea) for the uncatalysed reaction AND the activation energy (Ea cat) for the catalysed reaction. What does the difference between them represent?
Interactive: Toggle curves and labels above
[DIAGRAM] A student claims that because a catalyst lowers the activation energy, it also changes the overall energy change (ΔH) of the reaction. Using a reaction profile diagram, explain why this claim is incorrect.
Interactive: Toggle curves and labels above
The Haber process uses an iron catalyst. On a Maxwell-Boltzmann distribution diagram, show how a catalyst allows more particles to react at the same temperature. Label the activation energies for catalysed and uncatalysed reactions.
[EXTENDED] The industrial production of sulfuric acid (Contact Process) uses vanadium(V) oxide (V₂O₅) as a catalyst. (a) State the role of V₂O₅. (b) Explain using collision theory why the reaction would be too slow without a catalyst at the operating temperature of 450°C. (c) Why is the temperature not simply raised to increase the rate instead of using a catalyst?
⚡ Catalyst Fast Facts — Examiner's Cheat Sheet
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