posted by coleman on .
Determine whether Cd^2+ can be separated from Zn^2+ by bubbling H2S through a 0.3 M HCl solution that contains 0.005M Cd^2+ and 0.005 M Zn ^2+. Ksp for CdS is 8*10^-7. Ksp for ZnS is 3*10^-2
I don't have any of your data (and I don't believe the Ksp values either---they are far from correct) but here is what you do. You know H^+ is 0.3M, use that and the concn of a saturated solution of H2S to calculate (S^-2). Then
(Cd^+2)(S^-2) = Qsp
(Zn^+2)(S^-2) = Qsp
and compare with Ksp for each.
Using Ksp values for ZnS and CdS from my quant book, this will separate Zn from Cd (but my quant book Ksp values don't agree with your post).