Purpose and application of endothermic and exothermic reaction in all walks of chemistry​

Varies.Explanation:Exothermic and Endothermic properties are inherent in chemical reactions, one can not simply ascribe any purpose to them. However, we can utilize the properties for some of our practical purposes.Exothermic reactions are used as energy sources as such reactions generate heat. Other times, this generated heat can be problematic. For example, engines have chambers where chemical reactions happen; the exothermic nature generates heat which drives a car forward but also can create overheating which is a problem.Endothermic reactions do not generate energy, rather these reactions absorb energy. One needs to supply energy to cause these reactions. To burn Calcium Carbonate to produce Calcium Oxide and Carbon DiOxide, 425 kcals per kg energy is required.