What is a chemical substance that increases the rate of a chemical reaction?

A chemical substance that increases the rate of a chemical reaction is known as a catalyst. While "accelerator" is not the most commonly used term in scientific literature to refer to a catalyst, it can logically convey the idea of speeding up a reaction. Catalysts work by lowering the activation energy needed for a reaction to occur, allowing the reaction to proceed more quickly without being consumed in the process.

In contrast, an inhibitor is a substance that decreases the rate of a chemical reaction, making it the opposite of what the question is asking. A reagent is a substance that is used in a chemical reaction but does not specifically denote something that speeds up the reaction itself. A solvent is a substance that dissolves a solute, forming a solution, and does not increase the rate of chemical reactions in a direct manner. Therefore, while "accelerator" may not be the standard term, it effectively captures the essence of a substance that enhances reaction speed within the context of chemical processes.