Advanced Placement (AP) Chemistry Practice Exam 2025 - Free AP Chemistry Practice Questions and Study Guide

The statement that catalytic reactions do not change the overall energy of the reaction is indeed correct. Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy, which allows the reaction to proceed more quickly. However, the presence of a catalyst does not alter the overall energy change (enthalpy change) of the reaction; it merely facilitates the reaction's progress.

This means that while the activation energy is lowered, the reactants' energy, products' energy, and the overall energy change between the reactants and products remain the same. Thus, the nature of the chemical change and the thermodynamic properties of the reactants and products are unaffected by the addition of a catalyst.

In a broader context, while other statements regarding catalytic reactions may hold some merit, they do not encompass the fundamental nature of how catalysts function in terms of energy changes within a reaction.