Question

Calculate the solubility and solubility product of $C{o}_2\left[Fe\right(CN{)}_6]$ in water at ${25}^{\circ }C$ from the following data :

Conductivity of a structured solution of $C{o}_2\left[Fe\right(CN{)}_6]$ is $2.06\times {10}^{-6}{\Omega }^{-1}c{m}^{2}mo{l}^{-1}$ and $4.1\times {10}^{-7}{\Omega }^{-1}c{m}^{-1}$. The ionic molar conductivities of $C{o}^{2+}$ and $Fe(CN{)}_6^{4-}$ are $86.0{\Omega }^{-1}c{m}^{-1}$ and $444.0{\Omega }^{-1}c{m}^{-1}mol{e}^{-1}$.,then the $K_{sp}$ is:

• A. $7.682\times {10}^{-14}$
• B. $7.682\times {10}^{-18}$
• C. $3.841\times {10}^{-18}$
• D. $7.682\times {10}^{-17}$

Answer 1

The correct option is D $7.682\times {10}^{-17}$

${\lambda }_M=\frac{k\times 1000}{M}$
$(86\times 2+444)=\frac{(2.06\times {10}^{-6}-4.1\times {10}^{-7})\times 1000}{s}$
$s=2.678\times {10}^{-6}$
$K_{sp}=4s^3=7.687\times {10}^{-17}$