What is an exothermic reaction?

An exothermic reaction is defined as a chemical reaction that releases heat to its surroundings. This release of energy typically occurs in the form of heat, causing the temperature of the surroundings to increase. The process is characterized by a decrease in the internal energy of the reactants, which is transformed into thermal energy that is then released. This is why an exothermic reaction not only involves the liberation of heat but is also commonly associated with various types of combustion reactions, where substances like fuels react with oxygen.

The heat given off during an exothermic reaction results in practical applications, such as in heating systems, engines, and even in natural processes like respiration in living organisms, where energy is released as glucose is broken down. Understanding this type of reaction is crucial, particularly in industrial and laboratory contexts, as it informs how to manage reaction rates and thermal energy control within processes.