12. The following quantities of salts were added to a volume of water to make 1 liter of solution: 1 x 10-2moles NaCl 2 x 10-2 moles CaCl, 2 × 10-² moles BaCl, (a) What is the ionic strength of the solution? (b) A small amount of phosphate salt is added to the same solution with negligible change in ionic strength. Given K = 10-7-2 for the reaction H,PO,= H+ + HPO,?- Calculate [H*][HPO,²-]/[H,PO,"), called °K, using the Güntelberg ap- proximation of the DeBye-Hückel law. (c) Calculate the "salting-out" coefficient, k,, for a nonelectrolyte in the same solution if its activity is 10-3 M and its concentration is 9.5 x 10 M.

Metal sulfides are prepared by bubbling hydrogen sulfide gas, H, S, through an aqueous solution containing the metal ion, and then adjusting the pH. When the solution is saturated with H, S, which occurs when [H,S] = 0.100 M, the equilibrium shown is established. H, S(aq) + 2 H, O(1) = s²-(aq) + 2H,O*(aq) Keq = 1.1 x 10-20 An aqueous solution containing 0.0521 M Pb2+ and 0.0521 M Ag* is saturated with H, S. Above what concentration of S²- will PbS precipitate? The Kyp of PbS is 8.9 × 10-29. [s²-] = M Above what concentration of S²- will Ag,S precipitate? The Kşp of Ag,S is 3.3 × 10-50. [s²-] = M If the pH of the solution is adjusted to 2.32, which species will precipitate from the saturated H, S solution? both PbS and Ag,S PbS neither species O Ag,S

What is the molar solubility (in M to two decimal places) of cadmium carbonate in water (at 25 °C)? Ksp = 5.2 × 10–12

The solubility of salts that contain the conjugates of weak acids increase in acidic solution. Given the reaction of CUCN (Ksp = 3.47 x 10-20) with an acid in the form H3O+ shown below, find the equilibrium constant for this reaction given that Ka HCN = 4.9 x 10-10. CUCN(s) + H:O*(aq) = Cu"(aq) + HCN(aq) + H2O(1)