Question

What is an exothermic reaction? Give some examples.

Answer 1

There are two types of chemical reactions as per the energy of the reaction is concerned, in one type, energy is released while in the other, energy is absorbed. The former is exothermic while the latter is endothermic.

Complete step by step answer:
- There are certain reactions in which a certain amount of heat energy is liberated along the formation of the products. These reactions are called “Exothermic Reactions”. The heat is liberated due to the fact that the amount of energy required to break the bonds of the reactants involved is lower than the bond-formation energy of the products. And hence, the excess energy is liberated in the form of heat.
- For example, consider the case of burning of paraffins or alkanes such as butane which is a major component of the natural gas that is used as the fuel for cooking as compressed natural gas or CNG.
- When butane burns in air, the bonds between carbon and hydrogen are broken and are converted to carbon oxygen bonds of carbon dioxide which is more stable. Also the oxygen molecules are reduced to water molecules in the process. In the process almost of energy is released in the process which is the energy used to cook the food.
- Same thing happens for the burning of petrol and wood too. So they are also examples of exothermic reactions.

Note:
The opposite of the exothermic reaction is the endothermic reaction in which heat energy is taken to carry out the reaction. A common example is the conversion of the ice to water and water to water vapour.