Why only As+3 gets precipitated as As₂S₃ and not Zn+2 as ZnS when H₂S is passed through an acidic solution containing As+3 and Zn+2 ?
A.Solubility product of As₂S₃ is less than that of ZnS✓ Correct
B.Enough As+3 ions are present in acidic medium
C.Zinc salt does not ionise in acidic medium
D.Solubility product changes in presence of an acid.
Explanation
The species having minimum value of sp K will get precipitated first. It is because the ionic product will exceed the solubility product of such species. The sp K of 2 3 As S is less than ZnS. But in acidic medium ionization of 2 H S is suppressed due to common ion effect. Thus, sp K of ZnS does not exceed.