The Ksp of PbBr2 is 6.60 x 10^-6. What is the molar solubility of PbBr2 in a 0.500 M Pb(NO3)2 solution?

Answer 1

Common Ion Effect:

In this problem, the common ion is Pb²⁺ since it is present in both the PbBr₂ and the Pb(NO₃)₂.

PbBr2(s) <==> Pb2+(aq) + 2Br-(aq)

Ksp = [Pb²⁺][Br^-]²

[Pb²⁺] = 0.500 M (from the Pb(NO₃)₂

[Br-] = x (unknown)

6.60x10^-6 = [0.500][x]²

x² = 1.32x10^-5

x = 3.63x10^-3 M

Since x = [Br^-], the [Pb²⁺] = 1/2 x because there is 1 Pb²⁺ and 2 Br^- ions

Thus, the solubility of PbBr₂ in 0.500 M Pb(NO₃)₂ = 1.82x10^-3 M