What is the main way a catalyst increases the rate of a reaction?

• A. Increasing the overall energy change
• B. Changing the equilibrium constant
• C. Reducing the activation energy
• D. Consuming the catalyst

Answer: (C)

Catalysts speed up reactions by lowering the activation energy—the energy barrier that must be overcome for reactants to form products. By offering an alternate mechanism, often by stabilizing the transition state or forming short-lived intermediates, they allow more molecules to reach the necessary energy at a given temperature, so collisions that lead to product formation occur more frequently and the rate increases.

The overall energy change of the reaction doesn’t change, so the amount of heat released or absorbed remains the same. A catalyst also doesn’t shift the equilibrium position; it simply speeds up both forward and reverse processes, so the equilibrium constant stays the same. Finally, catalysts are not consumed in the reaction; they participate in the mechanism but are regenerated at the end of the cycle.