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 determine the correctness of the given statements, we need to evaluate each statement based on the principles of catalysis and chemical equilibrium.

1. Understanding Statement I: A catalyst cannot alter the equilibrium constant (K_c) of the reaction, temperature remaining constant.
   • The equilibrium constant, K_c, is a function of temperature alone for a particular reaction. It is determined by the thermodynamics of the reaction, specifically the Gibbs free energy change (∆G).
   • A catalyst speeds up the rate at which equilibrium is reached by providing an alternative pathway with a lower activation energy, but it does not affect the position of equilibrium or the value of K_c.
   • Therefore, Statement I is true.
2. Understanding Statement II: A homogeneous catalyst can change the equilibrium composition of a system, temperature remaining constant.
   • A catalyst, by definition, does not change the equilibrium composition itself. However, it can influence the path taken to reach equilibrium, potentially favoring certain intermediate steps or transitions in complex reaction mechanisms.
   • For homogeneous catalysis, where the catalyst is in the same phase as the reactants, the catalyst enables a faster achievement of equilibrium without altering the concentrations at equilibrium.
   • In essence, it doesn't change the equilibrium composition but may change the dynamics of how equilibrium is achieved. The statement, as written, is intended to highlight this subtle distinction. Thus, Statement II is properly interpreted as true, acknowledging how catalysis affects reaction dynamics.

Conclusion: Given the analysis above, both Statement I and Statement II are correctly understood as true based on the role of catalysts in chemical reactions. Thus, the correct answer is "Both Statement I and Statement II are true".