Which term is used to describe a substance that speeds up the rate of a chemical reaction?

The term that describes a substance that speeds up the rate of a chemical reaction is "catalyst." Catalysts work by providing an alternative reaction pathway with a lower activation energy, which allows the reaction to proceed more quickly without being consumed or permanently altered in the process. This means that a catalyst can facilitate the reaction repeatedly, making it a crucial component in various biological and chemical processes.

In contrast, other terms listed have different definitions. A reagent typically refers to a substance or compound added to a system to bring about a chemical reaction or to see if a reaction occurs; it does not necessarily speed up the reaction. A solvent is a substance—usually a liquid—that dissolves a solute, resulting in a solution, and it does not inherently increase the reaction rate. An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water, and is primarily involved in conducting electricity rather than catalyzing chemical reactions.