Question

Solubility Product

For the following questions, identify the ions comprising the salt, and then use the expression for the solubility product to perform the necessary calculations. This simple exercise involves the assumptions that you can ignore any complications which might result as a consequence of the basicity or acidity of the ions, ion pairing, complex ion formation, or auto-ionization of water.

a) Calculate the concentration, in mol/L, of a saturated aqueous solution of Hg₂I₂ (K_sp = 4.50×10^-29).
(Note: The mercurous cation is Hg₂²⁺ - cf Footnotes to Tables 2.4 & 8.5 in Zumdahl, Chemical Principles, 8th edn.)

answer in mol/L

b) Calculate the solubility, in g/100mL, of Hg₂I₂.

answer in g/100mL

c) Calculate the mass of PbSO₄ (K_sp = 1.30×10^-8) which will dissolve in 100 ml of water.

d) Rank the following five salts in order of decreasing solubility, in terms of mass per unit volume.  
(The most soluble gets rank 1, the least soluble gets rank 5.)

1 2 3 4 5  Hg₂I₂     (K_sp = 4.50×10^-29; Note: The cation is Hg₂²⁺)
1 2 3 4 5  Ca₅(PO₄)₃F     (K_sp = 1.00×10^-60)
1 2 3 4 5  Sr₃(PO₄)₂     (K_sp = 1.00×10^-31)
1 2 3 4 5  Ag₃PO₄     (K_sp = 1.80×10^-18)
1 2 3 4 5  PbSO₄     (K_sp = 1.30×10^-8)

Answer 1