Question

Which metal sulphide has maximum solubility in water?

• A. $CdS(K_{sp}=36\times {10}^{-30})$
• B. $FeS(K_{sp}=11\times {10}^{-20})$
• C. $Hgs(K_{sp}=32\times {10}^{-54})$
• D. $ZnS(K_{sp}=11\times {10}^{-22})$

Answer 1

Answer: (B)

$FeS(K_{sp}=11\times {10}^{-20})$

Solubility Product: In a saturated solution of a salt, there exists a dynamic equilibrium b/w the excess of the solute and ions furnished by that parts of the solute which has gone in solution. The solubility product of a sparingly soluble salt is given as product of the concentration of the ions raised to the power equal to the number of times the ion occur in the equation after the dissociation of the electrolyte.
So, metal sulphide with highest solubility product i.e $FeS$ will have maximum solubility in water in this case as all are di-ionic electrolyte.