What term describes a substance that speeds up the rate of a chemical reaction without being consumed?

• A. Reactant
• B. Inhibitor
• C. Catalyst
• D. Solvent

Answer: (C)

A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It works by providing an alternative reaction pathway that has a lower activation energy, so more particles have enough energy to react at a given temperature. Because the catalyst is not consumed, it remains available to catalyze additional reaction cycles, meaning it can continue to accelerate the reaction without its quantity diminishing. This is distinct from reactants, which are consumed as the reaction proceeds; inhibitors, which slow down or stop reactions; and solvents, which are the media in which reactions occur and do not inherently speed up the reaction unless they influence the system in a catalytic way. Catalysts also don’t change the final equilibrium composition; they only speed up how quickly equilibrium is reached by lowering the energy barrier for both forward and reverse directions.