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Question

Difficulty: MediumFactors Affecting Rates of Reaction

In a reversible chemical reaction, introducing a catalyst increases the rate of the forward reaction while leaving the rate of the reverse reaction unchanged.

Answer: Answer

Answer

The statement is False. A catalyst lowers the activation energy for both the forward and reverse reactions by the same amount, increasing both rates equally.
The statement is false because a positive catalyst lowers the activation energy threshold for both the forward and reverse reactions by the exact same amount. This speeds up both directions equally, allowing dynamic equilibrium to be established faster without changing the rate ratio or product yield.

Step-by-Step Solution

1
Examine the mechanism of catalytic action according to collision theory.
A catalyst provides an alternative reaction pathway with a lower activation energy (EaE_a).
Lowering the energy barrier increases the proportion of effective collisions per unit time.
2
Analyze how lowering activation energy impacts a reversible system.
The energy barrier is reduced by the exact same magnitude in both the forward and reverse directions.
The net enthalpy change (ΔH\Delta H) of the reaction is unchanged, so the peak height is reduced equally for both directions.
3
Evaluate the impact on reaction rates and equilibrium position.
Both forward and reverse reaction rates increase by the same factor.
Because both rates increase equally, the equilibrium position remains unaffected, making the assertion false.

Key Concept

Effect of Catalysts on Reaction Rates and Equilibrium
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Topics

Factors Affecting Rates of Reaction