Question

Given below are two statements:
Statement I: A catalyst cannot alter the equilibrium constant ($ K_c $) of the reaction, temperature remaining constant.
Statement II: A homogeneous catalyst can change the equilibrium composition of a system, temperature remaining constant.
In the light of the above statements, choose the correct answer from the options given below.

• A. Statement I is false but Statement II is true
• B. Both Statement I and Statement II are true
• C. Both Statement I and Statement II are false
• D. Statement I is true but Statement II is false

Hint:

A catalyst affects the rate of a reaction, but not the equilibrium constant. It can alter the equilibrium composition by changing the forward and reverse reaction rates equally.

Answer 1

The Correct Option is B

To assess the validity of the provided statements, each must be evaluated against the established principles of catalysis and chemical equilibrium.

1. Analysis of Statement I: A catalyst does not modify the reaction's equilibrium constant (K_c) when the temperature is held constant.
   • The equilibrium constant, K_c, is solely dependent on temperature for a given reaction, being determined by the reaction's thermodynamics, specifically the change in Gibbs free energy (∆G).
   • While a catalyst accelerates the attainment of equilibrium by offering an alternative pathway with reduced activation energy, it does not influence the equilibrium position or the value of K_c.
   • Consequently, Statement I is accurate.
2. Analysis of Statement II: A homogeneous catalyst can modify the equilibrium composition of a system at constant temperature.
   • By definition, a catalyst does not alter the equilibrium composition itself. However, it can influence the pathway to equilibrium, potentially favoring certain intermediate steps or transitions in complex reaction mechanisms.
   • In homogeneous catalysis, where the catalyst shares the same phase as the reactants, the catalyst facilitates a more rapid achievement of equilibrium without changing the equilibrium concentrations.
   • Fundamentally, it does not alter the equilibrium composition but may affect the kinetics of reaching equilibrium. The statement intends to highlight this nuanced aspect. Therefore, Statement II is considered true, recognizing the impact of catalysis on reaction dynamics.

Conclusion: Based on the preceding analysis, both Statement I and Statement II are deemed true concerning the function of catalysts in chemical reactions. The correct conclusion is "Both Statement I and Statement II are true".