• # question_answer 86)   What do you understand by exothermic reaction endothermic reaction? Give one example of each type.

Exothermic reaction: The chemical reaction which takes place with evolution of heat energy is called exothermic reaction. In this reaction, enthalpy change is negative. $C(s)+{{O}_{2}}(g)\to C{{O}_{2}}(g)+393.5kJ$ $2{{C}_{4}}{{H}_{10}}(g)+13{{O}_{2}}(g)\to 8C{{O}_{2}}(g)+10{{H}_{2}}O(g)+5316kJ$ Endothermic reaction: The chemical reaction which occurs with the absorption of energy is called endothermic reaction. In this reaction, enthalpy change is positive. ${{N}_{2}}(g)+{{O}_{2}}(g)+180.5kJ\to 2NO(g)$ $C(s)+2S(s)+92.0kJ\to C{{S}_{2}}(s)$ $S<P<O<P$