Exothermic reactions are chemical reactions that release heat energy into their surroundings. This results in an increase in temperature of the surrounding environment.
In these reactions, the energy of the products is lower than that of the reactants, because energy is given off—usually as heat or sometimes light. The release of energy makes exothermic reactions often feel warm or hot to the touch.
Examples of exothermic reactions include:
- Combustion (e.g., burning wood or fuel)
- Neutralization of acids and bases
- Condensation of steam
- Respiration in living organisms
Exothermic reactions are widely used in everyday life and industry—for instance, in heaters, fireworks, and explosives, or in self-heating packs. Their ability to release energy makes them highly useful for processes that require heat generation.