What is a catalyst?

A catalyst is accurately defined as a substance that increases the rate of a chemical reaction without undergoing any permanent change itself or being consumed in the process. This means that after the reaction, the catalyst can be recovered and used again in subsequent reactions. Catalysts work by providing an alternative pathway for the reaction to occur that has a lower activation energy, which allows the reaction to proceed more quickly.

In contrast, the other options describe different concepts. A substance that slows down a chemical reaction refers to an inhibitor, which is not what a catalyst does. A product formed by a chemical reaction pertains to the end result of a chemical process, rather than a substance that facilitates the reaction itself. Lastly, a type of chemical reaction that absorbs heat describes an endothermic reaction, which focuses on energy changes during the reaction rather than on the role of a catalyst. Understanding these distinctions clarifies the important role catalysts play in chemical reactions.