Consider the dissolution of MnS in water (K_sp = 3.0 * 10¯¹⁴). How is the solubility of manganese(II) sulfide affected by the addition of aqueous potassium hydroxide to the system? A) The solubility will be unchanged. B) The solubility will decrease. C) The solubility will increase. D) The amount of KOH added must be known before its effect can be predicted. E) The pK_a of H₂S is needed before a reliable prediction can be made.

Question

Quizplus · Accepted Answer

The dissolution of MnS in water involves the following equilibrium:

MnS (s) ⇌ Mn2+ (aq) + S2- (aq)

Adding aqueous potassium hydroxide (KOH) to the system will increase the concentration of hydroxide ions (OH-) in the solution. The OH- ions will react with the S2- ions to form hydroxide sulfide ions (HS-):

OH- (aq) + S2- (aq) ⇌ HS- (aq)

This will shift the equilibrium of the dissolution reaction to the left, decreasing the concentration of Mn2+ and S2- ions in the solution, and thus decreasing the solubility of MnS. Therefore, the correct answer is B.

Consider the Dissolution of MnS in Water (Ksp = 3

Consider the Dissolution of MnS in Water (K_sp = 3