Question

Which of the following salts has the greatest molar solubility in pure water?

• A. $CaC{O}_3;$ $K_{sp}=8.7\times {10}^{-9}$
• B. $CuS;$ $K_{sp}=8.5\times {10}^{-45}$
• C. $A{g}_{2}C{O}_3;$ $K_{sp}=6.2\times {10}^{-12}$
• D. $Pb(I{O}_3{)}_2;$ $K_{sp}=2.6\times {10}^{-13}$

Answer 1

Answer: (C)

$A{g}_{2}C{O}_3;$ $K_{sp}=6.2\times {10}^{-12}$

(A) For $CaC{O}_3,S=\sqrt{Ksp}=\sqrt{8.7\times {10}^{-9}}=9.3\times {10}^{-5}$ M

(B) For $CuS,S=\sqrt{Ksp}=\sqrt{8.5\times {10}^{-45}}=9.2\times {10}^{-23}$ M

(C) For $A{g}_{2}C{O}_3,S=(Ksp/4{)}^{1/3}=(6.2\times {10}^{-12}/4{)}^{1/3}=1.15\times {10}^{-4}$ M

(D) For $Pb(I{O}_3{)}_2,S=(Ksp/4{)}^{1/3}=(2.6\times {10}^{-13}/4{)}^{1/3}=4\times {10}^{-5}$ M

Hence, $A{g}_{2}C{O}_3$ has the greatest molar solubility in pure water.