Question

Calculate the solubility of Lead (II) Chloride in water.

Answer 1

Calculations for the solubility of Lead (II) Chloride in water is shown below.

For such low solubility compounds as PbCl₂ it is necessary to use the Ksp in order to determine solubility data. Ksp is based on solubility at 25°C :
Ksp for PbCl₂ = 1.70×10-5
PbCl₂ dissociates:
PbCl₂↔ Pb²⁺ + 2Cl^-
Let the molar solubility of PbCl₂ = X mol/L , then [Pb²⁺] = X and [Cl^-] = 2X
Ksp = [X] [2X]²
substitute and solve for X
1.70*10^-5 = X*4X²
1.70*10^-5 = 4X³
X³ = (1.70*10^-5) /4
X³ = 4.25*10^-6
X = 0.016M

The molar concentration of Pb²⁺ ions is 0.016M.
and the molar concentration of Cl^- ions is 0.032M.