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Difficulty: MediumReversible Reactions and Dynamic Equilibrium

In a closed chemical system at dynamic equilibrium, introducing a positive catalyst increases the rate of the forward reaction while leaving the rate of the reverse reaction unchanged, thereby increasing the overall equilibrium yield of products.

Answer: Answer

Answer

False. A positive catalyst lowers the activation energy barrier for both the forward and reverse reactions equally. As a result, both rates increase by the same factor, leaving the position of equilibrium and the product yield unchanged.
The statement is false because a catalyst lowers the activation energy for both the forward and reverse pathways by the same magnitude, thereby accelerating both rates equally and leaving the equilibrium position and product yield unaltered.

Step-by-Step Solution

1
Analyze how a catalyst affects the activation energy (EaE_a) of a reversible reaction.
A catalyst provides an alternative reaction mechanism with a lower activation energy for both the forward and reverse directions.
Since the energy profile is lowered symmetrically by ΔEa\Delta E_a, the energy barrier for the reverse reaction is reduced by the identical amount as the forward reaction.
2
Evaluate the effect of lowered activation energy on reaction rates.
The forward rate constant (kfk_f) and reverse rate constant (krk_r) both increase by the same proportional factor.
Because both rate constants increase equally, the forward and reverse reaction rates remain equal at the new accelerated pace.
3
Determine the impact on the equilibrium constant (KcK_c) and product yield.
The equilibrium constant Kc=kfkrK_c = \frac{k_f}{k_r} and the relative equilibrium concentrations of reactants and products remain unchanged.
A catalyst only affects the kinetic rate of reaching equilibrium, not the thermodynamic stability or position of equilibrium.

Key Concept

Effect of Catalysts on Dynamic Equilibrium and Activation Energy
Estimated Time:1m 0s
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Topics

Reversible Reactions and Dynamic Equilibrium