Question

Resistence of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is 100 $\Omega$ .The conductivity of this solution is $1.29S{m}^{-1}$ .Resistance of the same cell when filled with 0.02 M of the same solution is $520\Omega$ .The molar conductivity of 0.02 M solution of the electrolyte will be:

• A. $120\times {10}^{-4}S{m}^{2}mo{l}^{-1}$
• B. $1240\times {10}^{-4}S{m}^{2}mo{l}^{-1}$
• C. $1.24\times {10}^{-4}S{m}^{2}mo{l}^{-1}$
• D. $12.4\times {10}^{-4}S{m}^{2}mo{l}^{-1}$

Answer 1

Answer: (B)

$1240\times {10}^{-4}S{m}^{2}mo{l}^{-1}$

we have,

${\Delta }_m=\frac{k\times 1000}{M}$

${\Delta }_m=\frac{\frac{1}{R}\times cell-constant\times 1000}{M}$

$=\frac{\frac{1}{520}\times 1.29\times 100\times {10}^{-2}\times 1000}{0.02}$

$\therefore {\Delta }_m=124Sc{m}^{2}mo{l}^{-1}$