Which statement about catalysts is true?

Which statement about catalysts is true?

• A. They raise the activation energy
• B. They are consumed in the reaction
• C. They provide an alternative pathway with lower activation energy
• D. They have no effect on rate

Answer: (C)

Catalysts speed up reactions by providing an alternative mechanism with a lower activation energy. Visualize an energy diagram: the catalyzed path climbs over a smaller energy hill than the uncatalyzed path. Because the barrier is lower, more molecules have enough energy at the same temperature to reach the transition state, so the rate constant increases and the reaction proceeds faster. The catalyst itself is not consumed; it participates in the cycle and is regenerated, leaving the overall equation unchanged. Since the rate increases for both forward and reverse directions, the equilibrium composition is unchanged, just reached more quickly. This makes the statement about lowering the activation energy the best description of how catalysts work.

Catalysts speed up reactions by providing an alternative mechanism with a lower activation energy. Visualize an energy diagram: the catalyzed path climbs over a smaller energy hill than the uncatalyzed path. Because the barrier is lower, more molecules have enough energy at the same temperature to reach the transition state, so the rate constant increases and the reaction proceeds faster. The catalyst itself is not consumed; it participates in the cycle and is regenerated, leaving the overall equation unchanged. Since the rate increases for both forward and reverse directions, the equilibrium composition is unchanged, just reached more quickly. This makes the statement about lowering the activation energy the best description of how catalysts work.