What are substances that speed up chemical reactions without being consumed called?

Substances that speed up chemical reactions without being consumed in the process are known as catalysts. Catalysts work by lowering the activation energy required for a reaction to occur, thereby increasing the rate at which the reaction takes place. They facilitate the formation of transition states and help reactants come together in a more favorable arrangement, resulting in a faster reaction. Importantly, after the reaction has taken place, the catalyst remains unchanged and can be used repeatedly in multiple reactions, which is a crucial defining characteristic.

In contrast, inhibitors are substances that slow down or obstruct chemical reactions, and reagents refer to substances that are present at the start of a reaction and are transformed during the process. While enzymes serve as biological catalysts, their specific nature is tied to biochemical reactions, making them a subset of catalysts rather than the general term for all substances that increase reaction rates.