Question

4. Given the Ksp values below: Ksp(BaF2) 2.4 x 10-5 Kappor KspPbF2) = 4.0 x 10-8 KsplSrF2) = 0.8 x 10-10 If I increasingly add NaF to a solution with (Ba2+1=[Pb2')= [Sr2"]=0.01 M, what is the precipitation sequence? a. SrF2 first, then PbF2, and finally BaF2 b. BaF2 first, then PbF2, and finally SrF2 c. Not enough information to tell d. SrF2 first, then BaF2, and finally PbF2

Answer 1

For precipitation reaction, M² + (aq) + 2F M F (8) = [+2+] [F]2 Ksp - [M2+] [ro] Ionic product for saturated solution at any Concentration of solute, o If solubility product is smaller than the i onic product then excess solute Dill precipi- tate out because of the formation of Supersaturated solution, o Here, those solutions will form precipitate first which will have lesser solubility product Constant is Now, In the giren salt the Theresing value of k sp Ksp (Sufe) < Ksp ( PDF)<, Ksp (Baby) so, the corresponding rate of precipitation SoFz) Bat₂ Will be Pb F₂ Correct oplim is (a) a. Sof first, then Por and finally Batz