Question

In infinite dilutions, the molar conductances of Ba²⁺ and Cl^- are 127 and

76 . The equivalent conductivity of at infinite

dilution is

[CBSE 2000]

• A. 101.5
• B. 139.5
• C. 203.5
• D. 279.5

Answer 1

The correct option is

B

139.5$ohm{}^{-1}cm{}^{2}eq{}^{-1}$

1. Equivalent Conductivity is defined as the conducting power of all the ions produced by dissolving one gram equivalent of an electrolyte in a solution.

2. $BaCl{}_2⟶Ba{}^{+2}+2Cl{}^{-}$

3.${\lambda }_{BaCl{}_2}^{\infty }$ = ${\lambda }_{Ba{}^{+2}}^{\infty }$ + $2{\lambda }_{Cl{}^{-}}^{\infty }$

4. ${\lambda }_{BaCl{}_2}^{\infty }$ = $127+\left(2X76\right)=279$ $oh{m}^{-1}c{m}^{2}mo{l}^{-1}$

5. Since the equivalent weight of $BaCl{}_2$ = $\frac{Molecularweight}{2}$

6. Equivalent conductivity = $\frac{279}{2}=139.5$ $ohm{}^{-1}cm{}^{2}eq{}^{-1}$

Conclusive statement- Equivalent conductivity of $BaCl{}_2$ is 139.5$ohm{}^{-1}cm{}^{2}eq{}^{-1}$