Exothermic reaction is a chemical reaction that releases heat or energy into the surroundings. The enthalpy change of an exothermic reaction is negative, indicating that the products of the reaction have less energy than the reactants. This excess energy is released as heat, which can be measured using a calorimeter.

Some examples of exothermic reactions include:

* Combustion reactions, such as burning wood or gasoline

* Acid-base reactions, such as mixing hydrochloric acid and sodium hydroxide

* Precipitation reactions, such as mixing silver nitrate and sodium chloride

* Polymerization reactions, such as the curing of epoxy resin

Exothermic reactions are often used in everyday life, such as in heating homes and cooking food. They are also used in a variety of industrial processes, such as the production of steel and cement.

The opposite of an exothermic reaction is an endothermic reaction, which absorbs heat from the surroundings.