Question

How can a reaction lead to change in temperature? Explain the process.

Answer 1

Reactants → Products
In a chemical reaction, reactants combine with each other to form new products.
In the process, the bonds between the reactants break and new bonds are formed leading to the products.
All this happens because of energy change. When two or more reactants combine, some energy is needed for the bonds to break and some energy is released when new bonds are formed. When the energy of the products is lower than the energy of the reactants then heat is released to the surroundings leading to increase in the temperature of the reaction. This type of reaction wherein there is a net increase in the temperature of the system is called as exothermic reaction.
eg-
C + O₂ → CO₂ + heat

Another type of reaction is there where energy of the reactants is more than the products.​ In that case the net temperature of the reaction is decreased and these type of reactions are called endothermic reactions.
N₂ + O₂ + heat → 2NO