Exothermic endothermic chemical reactions

Introduction: there are two types of reactions on the basis of heat changes involved: exothermic reaction and endothermic reactions.

Exothermic reactions:
Those reactions in which heat is evolved are known as “exothermic reactions”.

For example:
(i) when carbon burns in oxygen to form carbon-di-oxide, a lot of heat is produced in this reaction:
                    C(s)       +    O₂ (g)   -------------------------->         CO₂ (g)          +        Heat
                Carbon          oxygen                                     carbon dioxide

The burning of carbon in oxygen is an exothermic reaction because heat is evolved in this reaction. AN exothermic reactions is indicated by the writing “+Heat” or “Heat energy” or just “+Energy” on the products’ side of an equation.

(ii)Respiration is also an example of exothermic reactions because energy is produced during this process. In respiration, glucose combines with oxygen in the cells of our body to form carbon dioxide and water along with production of energy:
C₆H₁₂O₆ (aq)     +         6O₂ (g)    ------------------------------->         6CO₂ (g)       +        6H₂O (l) +    Energy
(Glucose)                    (Oxygen)                                          (Carbon dioxide)           (Water)

Exothermic Endothermic Chemical Reactions : Endothermic Reaction

Endothermic reactions:
Those reactions in which heat is absorbed are known as “endothermic reactions”.

For example:
(i) When nitrogen and oxygen are heated to a very high temperature (of about 3000^o C) they combine to form nitrogen monoxide, and a lot of heat is absorbed in this reaction:
N₂ (g)         +       O₂ (g)      +    Heat   ---------------------->   2NO (g)
(Nitrogen)          (0xygen)                                             (Nitrogen monoxide)
The reaction between nitrogen and oxygen to form nitrogen monoxide is an endothermic reaction because heat is absorbed in this reaction. An endothermic reaction is usually indicated by writing “+Heat” or “+Heat energy” or just “+Energy” on the reactants side of an equation.
(ii)  All the decomposition reactions require energy ( in the form of light , heat or electricity) to take place. For example , when calcium carbonate is heated , it decompose to form calcium oxide and carbon dioxide:
      CaCo₃ (s)                +       heat  -------------------->        CaO (s)         +       CO₂ (g)
Calcium carbonate                                                     Calcium oxide          carbon dioxide