Question

Given the ionic conductance of $\begin{array}{c}CO{O}^{⊝}\\ |\\ CO{O}^{⊝}\end{array},K^{\oplus }$, and $N{a}^{\oplus }$ are 74,50 and $73c{m}^{2}oh{m}^{-1}e{q}^{-1}$, respectively. The equivalent conductance at infinite dilution of the salt $\begin{array}{c}COONa\\ |\\ COOK\end{array}$ is :

• A. $197c{m}^{2}oh{m}^{-1}e{q}^{-1}$
• B. $172c{m}^{2}oh{m}^{-1}e{q}^{-1}$
• C. $135.5c{m}^{2}oh{m}^{-1}e{q}^{-1}$
• D. $160.5c{m}^{2}oh{m}^{-1}e{q}^{-1}$

Answer 1

The correct option is C $135.5c{m}^{2}oh{m}^{-1}e{q}^{-1}$

Total charge =2

Number of equivalent of ion $=\frac{\text{change on the ion}}{\text{total charge}}$ $\therefore {\lambda }_{eq}^o\left(\begin{array}{c}COONa\\ |\\ COOk\end{array}\right)$

$\therefore$ Eq of $\left(\begin{array}{c}CO{O}^{⊝}\\ |\\ CO{O}^{⊝}\end{array}\right)=\frac{2}{2}=1$ $={\lambda }_{eq}^o\left(\begin{array}{c}CO{O}^{⊝}\\ |\\ CO{O}^{⊝}\end{array}\right)+\frac{1}{2}{\lambda }_{N{a}^{\oplus }}^o+\frac{1}{2}{\lambda }_{K^{\oplus }}^o$

Eq of $N{a}^{\oplus }=\frac{1}{2}$, Eq of $K^{\oplus }=\frac{1}{2}$ $=74+\frac{50}{2}+\frac{73}{2}=135.5$