Question

Why did PbCl2(s) dissolved in hot water, but AgCl(s) did not? Answer in term of Ksp and Delta H( which is endothermic)

Answer 1

Solubility Product(Ksp)

If an “insoluble” or slightly soluble material placed in water then there is Equilibrium between solid and ions in solution

for AgCl (s) =Ag⁺ (aq) + Cl^- (aq)

K = [Ag+ ] [Cl- ] Ksp is solubility product

Ksp (AgCl) = 1.7 x10^-10

Ksp (PbCl₂) = 1.6 x10^-5

More soluble then more ions in solution and Ksp is larger value

In hot water, PbCl₂

When the product exceeds Ksp the solution is supersaturated and precipitation occurs until the concentrations become small enough that their product does equal Ksp .

If more of either ion is added to a saturated solution so that the concentration product now exceeds Ksp, precipitation again occurs until the concentration product again reaches the Ksp magnitude due to common ion effect..