Exothermic process

In thermodynamics, an exothermic process (from Ancient Greek έξω (éxō) 'outward' and θερμικός (thermikós) 'thermal')[1] is a thermodynamic process or reaction that releases energy from the system to its surroundings,[2] usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen).

The term exothermic was first coined by 19th-century French chemist Marcellin Berthelot.

The chemical energy stored can be freed by the inverse (spontaneous) process: combustion of sugar, which gives carbon dioxide, water and heat (radiant energy).

[9] Exothermic refers to a transformation in which a closed system releases energy (heat) to the surroundings, expressed by When the transformation occurs at constant pressure and without exchange of electrical energy, heat Q is equal to the enthalpy change, i.e. while at constant volume, according to the first law of thermodynamics it equals internal energy (U) change, i.e.

[12] The transition of electrons from one quantum energy level to another causes light to be released.