A chemical reaction in which heat is given out to the surroundings - that is, there is a decrease in the enthalpy of the reaction mixture. An example of an exothermic reaction is the neutralization of an acid by a base.
Combustion reactions are exothermic.
For example, energy is released when fossil fuels are burned. The combustion of carbohydrates by living cells, to form carbon dioxide and water, is a biochemical example of an exothermic reaction and represents a major way in which many cells obtain their energy. An exothermic compound is one whose formation is accompanied by the liberation of heat. Oxford Paperback Encyclopedia 2. enthalpy Oxford Paperback Encyclopedia 3. All rights reserved.