Chapter 17: Solubility and Complex-Ion Equilibrium
Solubility from Ksp
What is the solubility of each of the following salts in water at 25oC?
- Barium sulfate
BaSO4
Ksp = 1.1 x 10-10
- Barium Fluoride
BaF2
Ksp = 1.0 x 10-6
- Aluminum hydroxide Al(OH)3
Ksp = 4.6 x 10-33
- Calcium Phosphate
Ca3(PO4)2
Ksp = 1.0 x 10-26
- Silver Chromate
Ag2CrO4
Ksp = 1.1 x 10-12
Ksp from Solubility
17.29 The solubility of silver bromate, AgBro3, in water is 0.0072 g/L. Calculate Ksp.
17.32 The solubility of silver dichromate, Ag2Cr2O7, in water is 1.59 g/L. Calculate Ksp.
17.33 The pH of a saturated solution of magnesium hydroxide was found to be 10.52. From this, find
Ksp for Mg(OH)2.
Common Ion Effect
17.39 What is the solubility of strontium sulfate, SrSO4, in 0.23 M sodium sulfate, Na2SO4, (Ksp(SrSO4)
= 2.5 x 10-7).
17.42 The solubility of silver sulfate, Ag2SO4, in water has been determined to be 8 g/L. What is the
solubility in 0.45 M sodium sulfate, Na2SO4?
Precipitation
17.45 From each of the following ion concentration in solution, determine whether a precipitate will
form in the solution.
a. [Ba2+] = 0.020 M, [F-] = 0.015 M
b. [Pb2+] = 0.035 M, [Cl-] = 0.15 M
17.47 Lead(II) Chromate, PbCrO4, was used as a yellow paint pigment. When a solution is prepared
that is 5.0 x 10-4 M in lead ion, Pb2+, and 5.0 x 10-5 M in chromate ion, CrO42-, would you expect a
precipitate to form?
17.51 A 45.0 ml sample of 0.015 M calcium chloride, CaCl2, is added to 55 ml of 0.010 M sodium
sulfate, Na2SO4. Is a precipitate expected to form?
17.55 What is the I- concentration just as AgCl begins to precipitate when 1.0 M AgNO3 is slowly added
to a solution containing 0.015 M Cl- and 0.015 M I-?
Effect of pH on Solubility
17.57 Write the net ionic equation in which the slightly soluble salt barium fluoride, BaF2, dissolves in
dilute hydrochloric acid.
17.59 Which salt would you expect to dissolve more readily in acidic solution, barium sulfate or barium
fluoride? Explain.
Extra: On addition of a dilute acid solution into saturated solutions of the following solutions interfaced
with excess precipitated salt, which salts would increase in solubility?
- CaCO3
- NaBr
- PbSO4
- MgSO3
- NH4Cl
Complex Ion Equilibrium
17.61 Write the chemical equation for the formation of the Cu(CN)2- ion. Write the Kf expression.
Calculate the solubility of AgBr on addition of 1.0 M NH3 into a saturated aqueous solution of the salt.
Compare this to the solubility of AgBr in pure water. (Ksp of AgBr = 5.0 x 10-13; Kf of Ag(NH3)2+ = 1.7 x 107)
Amphoteric Hydroxides
- Calculate the pH of a saturated Zn(OH)2(aq) solution. (Ksp = 2.1 x 10-16) . What is the solubility if
0.10 M NaOH is added to the solution? (Kf[Zn(OH)42-] = 2.8 x 1015).