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

The role of a catalyst in a chemical reaction is to lower the activation energy, which is the energy barrier that must be overcome for the reactants to transform into products. By providing an alternative pathway for the reaction, a catalyst allows the reaction to proceed more easily and quickly, facilitating the transformation without being consumed in the process. This means that the catalyst can participate in the reaction, helping to form the transition state, but ultimately, it is regenerated and remains unchanged at the end of the reaction.

Additionally, a catalyst does not alter the overall enthalpy change of the reaction, which is the energy difference between reactants and products. The enthalpy change remains the same regardless of whether a catalyst is present. Therefore, the option highlighting the catalyst's ability to lower activation energy while being unchanged is valid and essential to understand its function in chemical reactions.