Which factor can change the value of the equilibrium constant k for a given reaction?

Which factor can change the value of the equilibrium constant k for a given reaction?

• A. Concentration
• B. Pressure
• C. Presence of a catalyst
• D. Temperature

Answer: (D)

The value of the equilibrium constant is determined by temperature. At a fixed temperature, K is a constant that describes the balance between products and reactants once the system has reached equilibrium. This constant is related to thermodynamics and can be expressed through relationships like K = exp(-ΔG°/RT) or via the van't Hoff equation, which shows how ln K changes with temperature. Because ΔG° and the overall reaction enthalpy (ΔH°) depend on temperature, changing the temperature alters the relative favorability of the forward and reverse reactions, and thus changes K. If the reaction is exothermic, raising the temperature shifts the balance toward reactants and lowers K; if it is endothermic, raising the temperature shifts toward products and raises K. Changing concentrations or pressure moves the system along the same K value to re-establish equilibrium; the numerical value of K itself stays the same unless the temperature changes. A catalyst speeds up reaching equilibrium but does not alter the equilibrium constant.

The value of the equilibrium constant is determined by temperature. At a fixed temperature, K is a constant that describes the balance between products and reactants once the system has reached equilibrium. This constant is related to thermodynamics and can be expressed through relationships like K = exp(-ΔG°/RT) or via the van't Hoff equation, which shows how ln K changes with temperature. Because ΔG° and the overall reaction enthalpy (ΔH°) depend on temperature, changing the temperature alters the relative favorability of the forward and reverse reactions, and thus changes K. If the reaction is exothermic, raising the temperature shifts the balance toward reactants and lowers K; if it is endothermic, raising the temperature shifts toward products and raises K.

Changing concentrations or pressure moves the system along the same K value to re-establish equilibrium; the numerical value of K itself stays the same unless the temperature changes. A catalyst speeds up reaching equilibrium but does not alter the equilibrium constant.