Determine the value of the equilibrium constant (report
youranswer to three significant figures) for the following reaction
ifan equilibrium mixture contains 0.010 mol of solid
pbi2,and is 0.0100 m in pb2+ ions and 0.00081
m ini1- ions. use the notation 4.31e-5 to indicate a
numbersuch as 4.31 x 10-5.

Kps = 6.56e⁻⁹

Explanation:

This is a solubility equilibrium

PbI₂  (s)  ⇄  Pb²⁺  +  2I⁻

Expression for Kc will be:

[I⁻]²  . [Pb²⁺] / [PbI₂]

But we do not have to consider the solid. It does not have a physical sense.  Amount of solid without dissolving, doesn't affect the ions concentrations.

We talk about Kps (Constant for solubility product)

Kps = [I⁻]²  . [Pb²⁺]

Kps = (0.00081)²  .  0.01 → 6.56x10⁻⁹