3.7 Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
Conductivity(k) or specific conductance of a solution is defined as the inverse of resistivity.
Mathematically, it can be written as:-
In the above equation is the conductivity of a solution. Thus the definition of conductivity becomes as the conductance of a substance which is 1 cm long and has 1 sq. cm of cross-sectional area.
With dilution conductivity of a solution decreases due to an increase in distance between ions.\
Molar conductivity:- It is defined as the conductivity of a solution per unit concentration
It is clear from the above mathematical expression of the molar conductivity that, if we dilute the solution or decrease its concentration then molar conductivity increases. This is because, on dilution of a solution, a decrease in is more than compensated by the increase in its volume.