Question

The resistance of a $0.5M$ solution of an electrolyte in a cell was found to be $50\Omega$. If the electrodes in the cell are $2.2cm$ apart and have an area of $4.4c{m}^2$ then the molar conductivity (in $S{m}^{2}mo{l}^{-1}$) of the solution is:

• A. 0.2
• B. 0.02
• C. 0.002
• D. None of these

Answer 1

The correct option is B 0.02

$\text{Conductivity(k)}=\text{Conductance}\times \text{cell ~constant}$
$k=\frac{1}{50}\times \frac{2.2}{4.4}=0.01{\Omega }^{-1}c{m}^{-1}$
Molar conductivity, ${\Lambda }_m=k\times \frac{1000}{C}$
$\Rightarrow {\Lambda }_m=0.01\times \frac{1000}{0.5}=20{\Omega }^{-1}c{m}^{2}mo{l}^{-1}$
$\Rightarrow {\Lambda }_m=0.002{\Omega }^{-1}{m}^{2}mo{l}^{-1}$