Question

Why does molar conductance increases with dilution?

Answer 1

Molar Conductance:

• The conductance of volume $\mathrm{V}$ of a solution containing one mole of electrolyte held between two electrodes with an area of cross-section $\mathrm{A}$ and distance of unit length is the molar conductivity of a solution at a particular concentration.
• Formula of Molar conductance:

$\begin{array}{rcl}{\mathrm{Ʌ}}_{\mathrm{m}}& =& \frac{\mathrm{K}}{\mathrm{c}}\\ {\mathrm{Ʌ}}_{\mathrm{m}}& =& \mathrm{molar}\mathrm{conductivity}\\ \mathrm{К}& =& \mathrm{specific}\mathrm{conductivity}\\ \mathrm{c}& =& \mathrm{concentration}\mathrm{in}\mathrm{moles}\mathrm{per}\mathrm{volume}\end{array}$

Variation of molar conductance with dilution:-

• The conductance of a given solution having one mole electrolyte is referred as molar conductivity.
• Upon dilution, the degree of dissociation( fraction of the total number of moles which dissociate into ions) increases.
• As dissociation increases the number of ions increases and hence molar conductance increases with dilution.