What is an Exothermic Process?

An exothermic process is defined as a thermodynamic change where energy is transferred from a system to its surroundings. In chemical terms, this is represented by a negative standard enthalpy change (ΔH < 0).

The mechanism involves the conversion of chemical bond energy into thermal or electromagnetic energy. Because the activation energy required to initiate the reaction is lower than the energy released during the formation of new bonds, there is a net release of energy.

Exothermic reactions are generally more spontaneous than endothermic ones. They are fundamental to industrial processes, such as polymerization and the setting of concrete, as well as biological processes like cellular respiration.

The concept was formalized by 19th-century French chemist Marcellin Berthelot, who derived the term from the Ancient Greek 'exō' (outward) and 'thermikos' (thermal).

Examples span from simple combustion and acid-base neutralization to complex phenomena like nuclear fission in power plants and stellar nucleosynthesis in stars.