CBSE Class 12-science Answered

Molar conductivity of strong electrolytes: The curve obtained for strong electrolyte shows that there is only a small increase in conductance with dilution. This is because a strong electrolyte is completely dissociated in solution and so the number of ions remains constant. At higher concentrations, the greater inter-ionic attractions retard the motion of ions and, therefore, the conductance falls with increasing concentrations. With decrease in concentration, or with increase in dilution, the ions are far apart and therefore the interionic attractions decrease due to which the conductance increases with dilution and approaches a maximum limiting value at infinite dilution.

 

 

 

Molar conductivity of weak electrolytes: As a weak electrolyte dissociates to a much lesser extent as compared to a strong electrolyte, therefore, the conductance of a weak electrolyte is much lower than that of a strong electrolyte at the same concentration. Further, the curve obtained for a weak electrolyte shows that there is a very large increase in conductance with dilution especially near infinite dilution. This is because as the concentration of a weak electrolyte is reduced, more of it ionizes. Thus, increase in conductance with decrease in concentration is due to the increase in number of ions in the solution. However, it does not reach a limiting value.