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solubility product and ionic concentration

Answer the following questions that relate to solubility of salts of lead and barium:

A) A saturated solution is prepared by adding excess PbI2(s) to distilled water to form 1.0 L of solution at 25C. The concentrations of Pb2+ (aq) in the 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 = Pb2+ (aq) + 2 I- (aq)

(i) Write the equilibrium constant expression for the equation
(ii) Calculate the molar concentration of I- (aq) in the solution
(iii) Calculate the value of the equilibrium constant Ksp

B) A saturated solution is prepared by adding PbI2(s) to distilled water to form 2.0 L of solution at 25C. What are the molar concentrations of Pb2+ (aq) and I-(aq) in the solution? Justify your answer

C) solid NaI is added to a saturated solution of PbI2 at 25C. Assuming that the volume of the solution does not change, does the molar concentration of Pb2+(aq) in the solution increase , decrease or remain the same?. Justify your answer

D) the value of Ksp for the salt BaCrO4 is 1.2 x 10^-10. When a 500ml sample of 8.2 x 10 ^-6 M Ba( NO3)2 is added to 500ml of 8.2 x 10^-6 M Na2CrO4 , no precipitate is formed

(i). Assuming the volumes are additive, calculate the molar concentration of Ba2+ (aq) and CrO4 (aq) in the 1.00 L solution.
(ii). Use the molar concentrations of Ba2+ (aq) ions and CrO4 2- (aq) ions as determined above to show why a precipitate does not form. You must include a calculation as part of your answer.

Solution Summary

The solution analyzes the equilibriums of PbI2 and BaCrO4 solutions, respectively.