What is the role of a catalyst in a chemical reaction?

• A. To increase the rate of the reaction without being consumed.
• B. To change the equilibrium constant of the reaction.
• C. To provide the energy for the reaction to occur.
• D. To become a product of the reaction.

Answer: (A)

A catalyst works by giving the reaction a faster route through an alternative pathway that requires less energy to proceed, which lowers the activation energy for the process. This speeds up the rate at which reactants are converted to products, and the catalyst itself is not consumed in the reaction, so it can catalyze multiple cycles. Because it accelerates both the forward and reverse steps, the equilibrium constant—the ratio of products to reactants at equilibrium—stays the same, even though the system reaches that equilibrium more quickly. A catalyst does not supply energy to the reaction, nor does it become a permanent part of the final products. In practical terms, catalysts are regenerated at the end of the reaction, enabling repeated use, as seen with enzymes in biological systems or platinum catalysts in industrial processes.