In the context of chemical reactions, what does a catalyst do?

A catalyst plays a crucial role in chemical reactions by decreasing the activation energy required for the reaction to proceed. Activation energy is the minimum energy that reactant molecules must possess for a reaction to occur. By lowering this barrier, a catalyst allows more reactant molecules to possess sufficient energy to reach the transition state, leading to an increased rate of reaction without being consumed in the process.

This function of a catalyst does not affect the equilibrium constant of a reaction or alter the products formed, as it facilitates both the forward and the reverse reactions equally. Therefore, while the rate of reaction increases, the overall energy changes and equilibrium position remain unchanged.

In summary, the main effect of a catalyst is to enhance the speed of a reaction by reducing the activation energy, which ultimately leads to a more efficient reaction pathway without influencing the thermodynamic properties of the reactants and products.