Definition of Exothermic Reaction
Exothermic reactions or processes are such reactions in which the energy is released. The energy released is in the form of either heat or light. The reason behind the release of energy is that the total energy of the reactants is more than that of the total energy of the products. Hence, the enthalpy change is always negative for such reactions.
Example of Exothermic Reaction:
An example of an exothermic reaction is the reaction between a strong acid and water in which the acid would dissociate readily and release heat resultantly into the surroundings. The energy is released usually after the completion of the reaction.