What is the only factor that can alter Kc?

The equilibrium constant, Kc, is a measure of the ratio of concentrations of products to reactants at equilibrium for a given reaction at a constant temperature. The value of Kc is dependent solely on the temperature of the system; thus, changing the temperature is the only factor that can alter Kc.

When the temperature of a reaction system changes, it affects the rates at which products and reactants are formed, leading to a shift in the equilibrium position according to Le Chatelier's principle. This shift realigns the concentrations of reactants and products, resulting in a new value for Kc.

In contrast, pressure, volume, and concentrations of species involved in the equilibrium can affect the position of equilibrium itself, leading to a change in the amounts of reactants and products present at equilibrium. However, these changes do not affect the intrinsic value of Kc, which is tied exclusively to temperature. Therefore, while those factors can influence the dynamic equilibrium, they do not change the constant value Kc.