Question

Which of the following happens when a catalyst is added to a reaction at equilibrium?

• A. The point of equilibrium is shifted to the right
• B. The point of equilibrium is shifted to the left
• C. The forward and reverse reactions rates are increased uneqully
• D. The forward and reverse reactions rates are increased equally
• E. None of these

Answer 1

The correct option is D The forward and reverse reactions rates are increased equally

Adding a catalyst makes absolutely no difference to the position of equilibrium. This is because a catalyst speeds up the forward and back reaction to the same extent. Because adding a catalyst doesn't affect the relative rates of the two reactions, it can't affect the position of equilibrium. In other words, the value of the equilibrium constant is not affected but the equilibrium is quickly attained. Also, the value of $\Delta H$ is unaffected.