Catalysis in Chemical Reactions
Chemistry ⇒ Chemical Kinetics and Equilibrium
Catalysis in Chemical Reactions starts at 11 and continues till grade 12.
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A reaction has an activation energy of 80 kJ/mol. In the presence of a catalyst, the activation energy is reduced to 50 kJ/mol. By what amount has the activation energy decreased?
Describe the effect of a catalyst on the rate constant (k) of a reaction.
Describe the lock-and-key model of enzyme catalysis.
Describe the role of a catalyst in a chemical reaction in terms of activation energy.
Describe the term 'catalyst selectivity'.
Describe the term 'catalytic activity'.
Explain the difference between homogeneous and heterogeneous catalysis.
Explain why a catalyst does not appear in the overall balanced chemical equation for a reaction.
Explain why catalysts do not affect the enthalpy change (ΔH) of a reaction.
Explain why increasing the surface area of a solid catalyst increases its effectiveness.
Explain why temperature affects the activity of enzyme catalysts.
A certain reaction is catalyzed by a solid metal surface. If the surface becomes covered with product molecules, the reaction rate decreases significantly. Explain this observation in terms of catalysis.
A reaction has a rate constant k1 = 2.0 × 10−3 s−1 without a catalyst and k2 = 1.0 × 10−1 s−1 with a catalyst at the same temperature. By what factor has the rate constant increased due to the catalyst?
Consider the following reaction mechanism:
Step 1: A + B ⇌ C (fast equilibrium)
Step 2: C + D → E (slow, rate-determining step)
A catalyst X is introduced, which provides an alternative pathway:
Step 1: A + X → AX (fast)
Step 2: AX + B → C + X (fast)
Step 3: C + D → E (slow)
Explain how the presence of catalyst X affects the overall rate law and the reaction mechanism.
Describe the difference between a catalyst and an intermediate in a reaction mechanism.
Explain why increasing the concentration of a catalyst beyond a certain point does not further increase the rate of a reaction.
