Question

Which of the following has the highest degree of ionisation?
(A) 1M $N{{H}_{3}}$
(B) 0.001M $N{{H}_{3}}$
(C) 0.1M $N{{H}_{3}}$
(D) 0.0001M $N{{H}_{3}}$

Answer 1

Hint: An attempt to this question can be made by understanding the terms degree of ionization and dilution. Now we can devise a relation between the two terms. Based on this you can determine at what concentration of ammonia, the degree of ionization is highest.

Complete Solution :
- Dilution can be defined as the process of decreasing the concentration of a solute in a solution. Usually it is done by adding more solvent to the solution. Dilution is not limited to just liquids. The same theory is applicable in the case of gases as well.
- The degree of ionisation refers to the proportions of neutral particles like in a gas or aqueous solution that are later ionized to form ions or charged particles.
- It is observed that the degree of ionisation is directly proportional to dilution. This means that higher the dilution, higher will be the degree of ionisation.
- So, the solution having the least concentration of solute particles will have the greatest degree of ionisation.
So, the correct answer is “Option D”.

Note: It is often observed that the conductivity of a solution increases with dilution. This is because the concentration of solute decreases and they are free to move. However, it is important to know that although conductivity increases on dilution, the molar conductivity decreases upon dilution. This will help you avoid making mistakes in calculations.