This document discusses chemical reactions and their components. It explains that enzymes act as catalysts for reactions in living things and that hydrogen peroxide breaks down into water and oxygen in a chemical reaction, with hydrogen peroxide as the reactant and water and oxygen as the products. It also notes that it may not always be possible to determine reactants and products due to chemical equilibrium, and discusses the relationships between activation energy and bond energy as well as differences between endothermic and exothermic reactions.