Esoterminen

Esoterminen is a Finnish adjective that translates literally to “exothermic” in English. It is used primarily in chemistry and physics to describe processes that release heat or energy to their surroundings. The term originates from the Greek words “exo,” meaning outside, and “thermos,” meaning heat. In chemical reactions, an esoterminen reaction is one in which the activation energy is lower, and bonds that form in the products carry more binding energy than the bonds broken in the reactants, resulting in a net release of energy. The excess energy typically manifests as heat, but it can also produce light, sound, or other forms of energy.

Because heat flows from hot to cold, esoterminen reactions tend to be spontaneous and have a negative change in Gibbs free energy (ΔG < 0). The heat released raises the temperature of the system and its surroundings, often driving the separation of solvent and solute, the crystallization of solids, or the synthesis of high-energy compounds, such as explosives or nuclear fuels. Common examples include combustion of hydrocarbons, mixing water and cold solvent, and the neutralization of acids and bases.

In contrast, endothermic, or “intotherminen,” reactions absorb heat from their surroundings. Both types of reactions are crucial in industrial processes, biological metabolism, and environmental interactions. Scientific literature frequently compares esoterminen and intotherminen processes to understand energy balances, thermodynamic feasibility, and the design of efficient chemical systems.