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

The primary role of a catalyst in a chemical reaction is to provide an alternative pathway with lower activation energy. This is significant because activation energy is the minimum energy required for a reaction to occur. By lowering this energy barrier, a catalyst increases the rate at which a reaction proceeds.

This means that more reactant molecules can successfully collide with sufficient energy to result in a reaction, leading to an increase in the reaction rate without the catalyst being consumed in the process. Catalysts do not undergo permanent changes and can be recovered unchanged once the reaction is complete.

The other options do not accurately describe the role of a catalyst. While increasing temperature can indeed speed up reactions, it is not the function of a catalyst. Decreasing the concentration of reactants would not facilitate the reaction; instead, it would slow it down. Moreover, catalysts are not consumed during the reaction, nor do they serve as reactants; they merely assist in the reaction by altering the mechanism.