Flexi Says: Exothermic and endothermic are general terms that only tell whether the net energy flow of a chemical reaction is to or from the environment. In other words, exothermic reactions can give off any amount of energy. A quantity called the heat of reaction describes exact amount of energy that an exothermic reaction gives off, or an endothermic reaction absorbs. Heats of reaction are typically measured in kilojoules.
