What do catalysts, such as enzymes, primarily do in chemical reactions?

Catalysts, including enzymes, play a crucial role in chemical reactions primarily by lowering the activation energy required for the reaction to occur. Activation energy is the energy barrier that must be overcome for reactants to be transformed into products. By decreasing this energy barrier, catalysts enable reactions to proceed more easily and often at a faster rate, without being consumed in the process. This makes reactions more efficient, allowing biological and chemical processes to occur under milder conditions, such as lower temperatures and pressures.

While increasing temperature can also increase reaction rates, that isn't the specific role of a catalyst; it's an external factor that influences reaction kinetics. Catalysts do not form new substrates or change the natural direction of a reaction either; they facilitate the existing reaction pathways and do not alter the fundamental chemical equilibrium of the reaction. By understanding the unique function of lowering activation energy, we can appreciate why catalysts are essential in both biological systems and industrial applications.