Which term describes the starting substances in a chemical reaction?

• A. Catalysts
• B. Solvents
• C. Reactants
• D. Products

Answer: (C)

In a chemical reaction, the substances that start the process and undergo change are called reactants. They appear on the left side of a chemical equation and determine what’s reacting to form new substances. Products are what get formed as a result of the reaction, appearing on the right side. Catalysts speed up the reaction but are not consumed, so they aren’t considered starting materials. Solvents are the medium in which the reaction occurs; they’re not necessarily involved in the chemical change itself. For example, in the formation of water from hydrogen and oxygen, hydrogen and oxygen are the reactants, and water is the product. If a catalyst is used, it helps the reaction proceed more quickly but isn’t part of the final products.