Question

Density of solution is $1.20$g $m{L}^{-1}$ and molar mass of glucose is $180$ g $mo{l}^{-1}$] Resistance of conductivity cell filled with $0.1$M KCl solution is $100$ ohms. If the resistance of the same cell when filled with $0.02$ M KCl solution is $520$ ohms, calculate the conductivity and molar conductivity of $0.02$ M KCl solution. [Given: Conductivity of $0.1$M KCl solution is $1.29$ S $m^{-1}$].

Answer 1

Cell courtant G = conductivity $\times$ Resistance

$=1.29s/m\times 100-2=1.29$ unit

Conductivity of $0.02MKcl=$ cell courtant/ resistance

$=\frac{G}{R}=\frac{129m^{-1}}{520}=0.249s{m}^{-1}$

Concentration = $0.02M=1000\times 0.02=20mol{m}^{-3}$

Molar conductivity ${\wedge }_m=\frac{k}{c}=\frac{248\times {10}^{-3}s{m}^{-1}}{20mol{m}^{-3}}$

$=124\times {10}^{-4}s{m}^{2}mo{l}^{-1}$

$k=\frac{129c{m}^{-1}}{520}=0.248\times {10}^{-2}sc{m}^{-1}$

${\wedge }_m=k\times 1000c{m}^3{c}^{-1}{m}^{-1}$

$=\frac{0.248\times {10}^{-2}\times 1000}{0.02}=124sc{m}^2$