Question

What are Exothermic and Endothermic reactions? Given one example of each of them.

Answer 1

In chemistry there are a number of different reactions involved. They are depending from one factor to another. Like this, when we differentiate the reaction on the basis of the energy involved, we classify them into two, Endothermic reactions and Exothermic reactions.

Complete step by step answer:
We know that a chemical reaction either absorbs energy or releases energy in the form of light sound or heat. Let us look into endothermic and exothermic reactions.
Endothermic reaction describes a reaction when the system absorbs its energy in the form of heat from its surroundings whereas exothermic reaction describes a reaction when the system releases the energy in the form of light or heat to its surroundings. Hence, we can say that exothermic reactions are opposite to endothermic reactions.
Now, let us look into some examples.
The most popular example of endothermic reaction is during the process when plants absorb energy from the sun and convert it into carbon dioxide and water. Since the sun absorbs the energy it makes the chemical reaction an endothermic reaction. An example for exothermic would be the reaction between sodium and chloride where the product we obtain is sodium chloride also known as common salt. Since the energy is released in this chemical reaction, we say it is an exothermic reaction.
Hence, option (A) is correct.

Note: We can also say that when the energy of products is greater than energy of reactants; in this case we say it is an endothermic reaction ;whereas when the energy of reactants is greater than energy of products; in this case we say; it is an exothermic reaction.