Which best describes an exothermic reaction?

An exothermic reaction is characterized by the release of energy, primarily in the form of heat, to the surroundings. This often results in a temperature increase in the environment where the reaction takes place. During this type of reaction, the total energy of the products is lower than that of the reactants, meaning that energy is given off as the reaction proceeds.

In practical terms, examples of exothermic reactions include combustion (like burning wood or gasoline) and many types of chemical reactions that involve the formation of stronger bonds in the product molecules compared to the weaker bonds in the reactant molecules. The distinction is important because many natural processes, such as respiration in living organisms and various industrial processes, rely on exothermic reactions to release energy for use.

Understanding that an exothermic reaction is associated with energy release helps in grasping concepts related to thermodynamics and energy transfer in physical science.