Question

What minimum concentration of cl− is required to begin to precipitate pbcl2? for pbcl2, ksp=1.17×10−5?

Answer 1

TO determine the minimum concentration that is required, we write the solubility constant expression from the dissociation reaction of the compound. It would be as follows:

PbCl2 = Pb2+ + 2Cl-

Ksp = [Pb2+] (2[Cl-])^2
1.17×10−5 = (x)(4x^2) = 4x^3
x = 0.0143 M

Therefore, the minimum concentration of Cl- would be 2(0.0143) = 0.0286 M.