What role does a catalyst play in a chemical reaction?

A catalyst plays a crucial role in chemical reactions by speeding up the reaction rate without being consumed in the process. This means that while a catalyst facilitates the conversion of reactants into products, it does not undergo any permanent changes itself and can be reused multiple times. Catalysts work by providing an alternative mechanism or pathway for the reaction to occur, which typically has a lower activation energy compared to the non-catalyzed reaction. This allows more molecules to have sufficient energy to collide and react, increasing the reaction rate effectively.

The other options do not accurately describe the function of a catalyst. For instance, a catalyst does not increase the amount of product formed; it merely accelerates how quickly the products are generated from the reactants. Similarly, a catalyst does not change the temperature of a reaction; it affects the rate of the reaction rather than the overall energy balance or thermodynamics. Additionally, a catalyst does not alter the direction of a reaction; it simply makes it proceed more quickly in the direction that is already favored by the system's conditions.