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

A catalyst serves the primary purpose of accelerating the reaction rate in a chemical process. It achieves this by providing an alternative pathway for the reaction that has a lower activation energy compared to the uncatalyzed reaction. This means that more reactant molecules can achieve the necessary energy to transform into products in a given amount of time, thus speeding up the overall reaction without being consumed in the process.

Catalysts do not alter the products of the reaction, hence they maintain selectivity towards the original reactants. While catalysts can sometimes affect the energy profile of a reaction—such as by decreasing the activation energy—they do not directly increase the temperature of the reaction system itself. Additionally, while lowering the activation energy is an important aspect of how catalysts work, their critical function is fundamentally about increasing the reaction rate. Thus, the correct answer reflects the primary role a catalyst plays in enhancing the efficiency of chemical reactions.