What characterizes an exothermic reaction?

An exothermic reaction is characterized by its ability to release energy, typically manifesting as heat, into the surroundings. This release of energy is a result of the chemical bonds being formed during the reaction process, which generally results in the products having lower energy than the reactants. As a consequence, the surroundings experience an increase in temperature, which is a hallmark of exothermic processes.

Other options describe different types of reactions or scenarios. The first option refers to endothermic reactions, which absorb energy rather than release it. The third option mistakenly suggests that catalysts are necessary for exothermic reactions, while catalysts are typically related to the rate of reactions rather than energy changes. The fourth option inaccurately describes the temperature change associated with exothermic reactions, which actually leads to an increase in temperature rather than a decrease. Understanding the energy flow and temperature changes associated with chemical reactions is crucial in distinguishing between different types of reactions.