Answer:
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