Chemistry Regents Practice Test 2025 – The All-in-One Guide to Exam Success!

A catalyst plays a crucial role in a chemical reaction by lowering the activation energy needed for the reaction to occur. Activation energy is the minimum energy that reactants must possess for a reaction to proceed. By decreasing this energy barrier, catalysts allow more reactant particles to collide with sufficient energy, thus increasing the rate at which the reaction occurs without being consumed in the process.

The presence of a catalyst does not change the reaction temperature or pressure. While external conditions such as temperature and pressure can influence reaction rates, the primary function of a catalyst is specifically related to the energy dynamics of the reaction. Additionally, catalysts do not alter the products of a reaction; they simply facilitate the formation of the products at a faster rate. Thus, the correct understanding of a catalyst's role aligns perfectly with the option that states it decreases the activation energy required for the reaction.