Question

What is the effect of dilution on molar conductance and conductivity?

Answer 1

Conductivity changes with the concentration of the electrolyte. The number of ions per unit volume carrying the current decreases on dilution, so conductivity always decreases with decrease in concentration. However, molar conductivity increases with dilution.

Answer 2

Explanation:

When one mole of electrolyte is dissolved in solution then the ions will gain a conducting power. This is known as molar conductance.

Mathematically, $Molar conductance = \frac{K}{M}$

where  K = specific conductance

            M = electrolyte concentration

On dilution there will be increase in the concentration of ions, thus from the above equation it can be seen that molar conductance is inversely proportional to the electrolyte concentration.

Therefore, when there is increase in concentration of ions then there will be decrease in molar conductance.

Also, as the concentration of ions increases upon dilution so, there will me more number of ions which will move freely from one place to another. As a result, there will be increase in conductivity also.

Therefore, we can conclude that increase in dilution will decrease molar conductance and increase in dilution will increase conductivity.