Which of the following would decrease the Ksp of PbI2?
A. lowering the pH of the solution
B. adding Pb(NO3)2 to the solution
C. adding KI to the solution
D. adding a reagent that would form a complex ion with Pb2+ E none of the above

Question

Which of the following would decrease the Ksp of PbI2?
A. lowering the pH of the solution
B. adding Pb(NO3)2 to the solution
C. adding KI to the solution 
D. adding a reagent that would form a complex ion with Pb2+ E none of the above

anonymous · Answer

C. if you already have an ion present in solution, then the solubility of the additional salt will decrease. C is better than B because the molecule PbI2 has two iodide atoms, so solubility will decrease the most when we have iodide already present.