Ace Your HESI A2 Chemistry Test 2025 – Ignite Your Path to Nursing Success!

A catalyst plays a crucial role in chemical reactions by increasing the rate of the reaction without being consumed in the process. It achieves this by providing an alternative pathway for the reaction with a lower activation energy. This means that more reactant molecules can acquire the necessary energy to undergo the reaction, leading to an increased rate of reaction.

In the presence of a catalyst, the energy barrier that reactants must overcome to form products is reduced, allowing the reaction to occur more readily and efficiently. Importantly, once the reaction is complete, the catalyst remains unchanged and can be reused for subsequent reactions. This characteristic makes catalysts vital in various industrial processes and biological systems, such as enzymes in metabolic pathways.

The roles of other substances mentioned in the options differ significantly from that of a catalyst. A substance that decreases the rate of the reaction would act as an inhibitor, while one that provides energy would typically refer to an external energy source rather than a catalyst. Additionally, changing the direction of the reaction pertains to factors that influence equilibrium, not the function of a catalyst.