Which statement correctly describes how a catalyst affects a reaction?

Which statement correctly describes how a catalyst affects a reaction?

• A. It increases the amount of product formed.
• B. It alters the final equilibrium concentration of reactants and products.
• C. It lowers the activation energy, speeding up both forward and reverse reactions without changing the overall amount of product.
• D. It is consumed in the reaction and must be replenished.

Answer: (C)

A catalyst works by providing an alternative pathway for the reaction that has a lower activation energy. Because this energy barrier is lower, more molecules can rearrange and react per unit time, so the rate of the reaction increases. Importantly, this speeding up happens for both the forward and the reverse directions, so the system reaches equilibrium faster, but the actual balance between reactants and products at equilibrium stays the same. A catalyst is not consumed in the reaction, so it doesn’t change the total amount of product that can form; it just helps reach that amount more quickly. So the statement is the best fit because it captures both the speed-up of the process and the fact that the final yields and equilibrium concentrations remain unchanged by the catalyst.

A catalyst works by providing an alternative pathway for the reaction that has a lower activation energy. Because this energy barrier is lower, more molecules can rearrange and react per unit time, so the rate of the reaction increases. Importantly, this speeding up happens for both the forward and the reverse directions, so the system reaches equilibrium faster, but the actual balance between reactants and products at equilibrium stays the same. A catalyst is not consumed in the reaction, so it doesn’t change the total amount of product that can form; it just helps reach that amount more quickly. So the statement is the best fit because it captures both the speed-up of the process and the fact that the final yields and equilibrium concentrations remain unchanged by the catalyst.