Which factor does not affect the value of Kc in a chemical reaction at equilibrium?

The value of the equilibrium constant, Kc, is a specific ratio of the concentrations of products to reactants raised to the power of their stoichiometric coefficients in a balanced chemical equation. It is fundamentally linked to the nature of the reaction and the temperature at which it occurs.

Temperature is crucial because Kc is temperature-dependent; changing the temperature alters the equilibrium position and therefore the concentrations of the products and reactants at equilibrium, which subsequently affects Kc.

The concentration of reactants can shift the position of equilibrium according to Le Chatelier’s principle, but it does not directly change the value of Kc. Instead, it changes which side of the equilibrium is favored until a new equilibrium is established.

For gaseous reactions, pressure can also influence the position of equilibrium by favoring the side of the reaction with fewer moles of gas, but like concentration, it does not change the value of Kc itself; it merely impacts the equilibrium concentrations until a new equilibrium is reached.

Conversely, the presence of a catalyst speeds up the rate of both the forward and reverse reactions equally without altering the energy levels of the reactants or products. Therefore, while a catalyst helps the system reach equilibrium more quickly, it does not affect the concentrations of