During the metathesis between an acid and base in addition to water and salt energy is also released. Such processes where system gives off heat to its surroundings is called an exothermic process. During an exothermic chemical reaction the internal energy of products is less than that of reactants. That being said, the stability of the products should be higher than the stability of the reactants. This stability difference can be simply related to the difference in the stored chemical potential energies, in term of chemical bondings. In this experiment the heat of reaction, which will be measured in constant pressure will guide us to estimate enthalpy of neutralization reaction:.