* Common Ion Effect: The common ion effect states that the solubility of a sparingly soluble salt decreases when a soluble salt containing a common ion is added to the solution.
* In this case:
* PbI₂ is a sparingly soluble salt.
* KI is a soluble salt that provides iodide ions (I⁻).
* The addition of KI to a solution containing PbI₂ increases the concentration of iodide ions, which is a common ion.
* Result: The increased concentration of iodide ions shifts the equilibrium of the dissolution of PbI₂ to the left, favoring the formation of solid PbI₂ and reducing the solubility of PbI₂.
In summary: The presence of a common ion (iodide) in the KI solution reduces the solubility of lead(II) iodide.
