What is defined as any substance that accelerates a reaction without undergoing a chemical change itself?

A catalyst is a substance that increases the rate of a chemical reaction without being consumed or undergoing any permanent chemical change itself. This definition encompasses both chemical catalysts and biological catalysts known as enzymes. Catalysts work by providing an alternative pathway for the reaction that has a lower activation energy, thereby allowing the reaction to proceed more rapidly.

In chemical processes, catalysts can be metals or other compounds that remain unchanged after the reaction has taken place. For enzymes, which are biological catalysts, they are typically proteins that facilitate biochemical reactions in living organisms. Their specificity and efficiency in speeding up biochemical reactions are essential for various metabolic processes without altering the enzyme’s own structure.

While other terms such as reactant, enzyme, and inhibitor relate to chemical processes, they do not describe this specific function of accelerating reactions without undergoing change. A reactant is a substance that participates in a chemical reaction and is consumed during the process. An enzyme is indeed a specific type of catalyst but is more narrowly defined as a protein that facilitates biological reactions. An inhibitor, on the other hand, is a substance that slows down or prevents a chemical reaction, which is the opposite function of a catalyst.