Which type of chemical reaction releases energy?

A chemical reaction that releases energy is identified as an exothermic reaction. During this type of reaction, the total energy of the products is less than that of the reactants. As the reaction takes place, energy is released, often in the form of heat or light. This energy release occurs because the formation of new bonds in the products releases more energy than is required to break the bonds in the reactants. Common examples of exothermic reactions include combustion and certain types of oxidation reactions.

Although combustion reactions, which are a specific type of exothermic reaction, also release energy, not all exothermic reactions are combustion reactions. Similarly, while decomposition reactions can be endothermic (absorbing energy), this does not apply to all decomposition reactions, making it essential to distinguish between different types of reactions based on their energy profiles. Thus, the classification of an exothermic reaction encompasses a wider range of reactions where energy is released.