A saturated solution is prepared by adding excess PbI2 (s) to distilled water to form 1.0L of solution at

25°C. The concentration of Pb
2+
(aq) in the same saturated solution is found to be 1.3 x 10
-3 M. The

chemical equation for the dissolution of PbI2

(s) in water is shown below.

PbI2
(s) ⇄ Pb
2+
(aq) + 2 I
-
(aq)

a. Write the equilibrium-constant expression for the equation
b. Calculate the molar concentration of I
-
(aq) in the solution
c. Calculate the value of the equilibrium constant, Ksp
d. An additional 1.0 L of water is added, bringing the total volume of the solution to 2.0 L and the
solution remains saturated. Calculate the molar concentration of Pb
2+
(aq) in the solution.

e. Solid NaI is added to the saturated solution of PbI2

. Assuming the volume of the solution does

not change, does the molar concentration of Pb
2+
(aq) in the solution increase, decrease, or

remain the same? Justify your answer.