Exothermic reaction

An exothermic reaction is a chemical reaction that releases energy through light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy.Exothermic Reaction means 'exo' (derived from the greek word: 'έξω', literally translated to 'out') meaning releases and 'thermic' means heat. So the reaction in which there is release of heat with or without light is called exothermic reaction. An exothermic reaction is a chemical reaction that releases heat. It gives net energy to its surroundings. That is, the energy needed to initiate the reaction is less than the energy released. When the medium in which the reaction is taking place collects heat, the reaction is exothermic.When using a calorimeter, the total amount of heat that flows into (or through) the calorimeter is the negative of the net change in energy of the system. The absolute amount of energy in a chemical system is difficult to measure or calculate. The enthalpy change, ΔH, of a chemical reaction is much easier to work with. The enthalpy change equals the change in internal energy of the system plus the work needed to change the volume of the system against constant ambient pressure. A bomb calorimeter is very suitable for measuring the energy change, ΔH, of a combustion reaction. Measured and calculated ΔH values are related to bond energies by: