The concentration of sulphide ion in 0.1M HCl solution saturated with hydrogen sulphide is 1.0×10−19M. If 10 mL of this is added to 5 mL of 0.04 M solution of the following:
FeSO4,MnCl2,ZnCl2 and CdCl2. in which of these solutions precipitation will take place?
For precipitation to take place, it is required that the calculated ionic product exceeds the Ksp value.
[S2−]=1.0×10−19M and [M2+]=0.04M
volume = 10 mL volume = 5mL
Ionic product =[M2+][S2−]=(1.33×10−2)(6.67×10−20)=8.87×10−22
This ionic product exceeds the Ksp of Zns and CdS. Therefore, precipitation will occur in CdCl2 and ZnCl2 solutions.