
CHEM 160
Solubility Equilibria
Chapter 17 Example Problems
This list of solubility equilibria problems contains problems that will be worked as
examples in class and additional problems for students to try on their own.
1. Calculate the K for MgF if the molar solubility of this salt is 2.7 x 10-3 M.
sp 2
Ans. 7.9 x 10-8
2. Calculate the Ksp for Ca3(PO4)2 (FW = 310.2) if the solubility is 8.1 x 10-4 g/L.
Ans. 1.3 x 10-26
3. Calculate the K for La(IO ) if the molar solubility of this salt is 7.8 x 10-4 M.
sp 3 3
Ans. 1.0 x 10-11
4. The Ksp for CaF2 (FW = 78) is 4.0 x 10-11. What is the molar solubility of CaF2 in water?
What is the solubility of CaF2 in water in g/L? Ans. 2.2 x 10-4 M, 0.017 g
5. The Ksp for BaCO3 is 5.0 x 10-9. What is the molarity of a saturated aqueous solution of
BaCO3? Ans. 7.1 x 10-5 M
6. The Ksp for Fe(OH)2 is 4.1 x 10-15. What is the approximate pH of a saturated solution of
Fe(OH)2? Ans. 9.00
7. Calculate the IP for PbF2 (Ksp = 4.1 x 10-8) when 500.0 mL of 0.0030 M Pb(NO3)2(aq) and
800.0 mL of 0.0040 M NaF(aq) are mixed? Will a precipitate of PbF2 form in the solution?
Ans. IP = 7.5 x 10-9, No
8. Calculate the IP for PbF2 (Ksp = 4.1 x 10-8) when 500.0 mL of 0.0030 M Pb(NO3)2(aq) and
800.0 mL of 0.040 M NaF(aq) are mixed? Will a precipitate of PbF form in the solution?
2
Ans. IP = 7.5 x 10-7, Yes
9. Will a precipitate of CaCO3 (Ksp = 4.5 x 10-9) form when 0.500 g of solid Na2CO3 (FW =
106.0) are added to 250.0 mL of 0.0030 M Ca2+(aq)? Assume no volume change.
Ans. IP = 5.7 x 10-5, Yes
10. A student carefully adds solid silver nitrate, AgNO3, to a 0.0030 M solution of sodium
sulfate, Na2SO4. What [Ag+] in the solution is needed to just initiate precipitation of silver
sulfate, Ag2SO4 (Ksp = 1.4 x 10-5). Ans. 0.068 M
11. What is the molar solubility of AgCl in a 0.02 M NaCl solution? What is the molar
solubility of AgCl in water? (Ksp for AgCl = 1.7 x 10-10) Ans. 8.5 x 10-9 M, 1.3 x 10-5 M
12. Calculate the molar solubility of CaF2 (Ksp 4.0 x 10-11) in a solution that contains (a) 0.10 M
Ca2+ and (b) 0.10 M NaF. Ans. (a) 1.0 x 10-5 M, (b) 4.0 x 10-9 M
1