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

Hint: We know that in the given question the solubility of the Sulphide has been discussed. Sulphide can be soluble in various solutions therefore in the answer solubility of the metal Sulphide especially in acidic solution is discussed.

Complete answer:
There are only some metal sulfides which are soluble in acid or can say acid-hydrolysable they are Zinc Sulphide, Cadmium Sulphide, Nickel Sulphide, Copper Sulphide, and copper Sulphide rather than that there are other insoluble sulfides such as iron Sulphide, Molybdenum Sulphide and others. Many sulfide salts are insoluble in acidic solution are lead Sulphide, Bismuth Sulphide, Copper Sulphide, Cadmium Sulphide, mercuric Sulphide, arsenic Sulphide and more.
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 those parts of the solute which has gone in solution. The solubility product of a sparingly soluble salt is given as a product of the concentration of the ions raised to the power equal to the number of times the ion occurs 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 electrolytes.

Therefore, the correct answer is option B.

Additional Information:
Sulfide is an inorganic anion of sulfur which has the chemical formula or we can say a compound containing one or more ions. Solutions of sulfide salts are corrosive in nature. The solubility of the compounds depends mainly on the pH of the solution. The alkali metals and alkaline-earth metals are the only sulfides that can have considerable water solubility.

Note:
Remember that the sulfides of all metals except barium, calcium, magnesium, sodium, potassium, and ammonium are insoluble in water. Barium Sulphide, Calcium Sulphide, and Magnesium Sulphide are sparingly soluble in water.