General Chemistry, 11e (Petrucci)
Chapter 18 Solubility and Complex-Ion Equilibria
1) Some solid in a solution at equilibrium means the solution is saturated.
2) A solute’s molar solubility and its molarity are not the same in a saturated aqueous solution.
3) The common ion effect is a case of Hess’s law.
4) The diverse ion effect is also called the salt effect.
5) Ion pairs as a limitation to Ksp are more likely to be a problem with NaCl than with MgSO4.
6) If Qsp is larger than Ksp, precipitation should occur.
7) Fractional precipitation is a method to precipitate only part of the concentration of an ion.
8) The pH of a solution may affect solubility only if the salt contains the OH– ion.
9) Qualitative cation analysis has been replaced in recent years by instrumental analysis.
10) A small amount of solid calcium hydroxide is shaken vigorously in a test tube almost full of water
until no further change occurs and most of the solid settles out. The resulting solution is:
A) concentrated and saturated
B) dilute and saturated
C) dilute and unsaturated
D) dilute and supersaturated
E) concentrated and supersaturated
11) The molar solubility of SrSO4 (Ksp = 7.6 × 10-7) is:
A) 2.8 × 10-5 M
B) 7.6 × 10-7 M
C) 8.7 × 10-8 M
D) 8.7 × 10-4 M
E) 9.1 × 10-3 M
12) What is the molar solubility of barium carbonate in pure water? (Ksp = 5.1 × 10-9)
A) 5.1 × 10-9 M
B) 7.1 × 10-5 M
C) 1.1 × 10–3 M
D) 1.7 × 10–3 M
E) 2.6 × 10-17 M
13) The solubility of magnesium fluoride is 1.17 × 10-3 M. Find the value of Ksp for this compound.
A) 1.17 × 10–3
B) (1.17 × 10-3)2
C) 4(1.17 × 10-3)3
D) (1.17 × 10-3)3
E) 3(1.17 × 10-3)3
14) The solubility of CaF2 is 0.00021 mole per liter. What is the solubility product constant for CaF2?
A) 7.3 × 10-12
B) 3.7 × 10-11
C) 8.5 × 10–8
D) 4.4 × 10–8
E) 1.9 × 10-11
15) The solubility of copper(II) iodate Cu(IO3)2 is reported as 0.12 g per 100 mL. What is the solubility
product constant for this salt?
A) 9.8 × 10–8
B) 8.6 × 10–7
C) 7.3 × 10–6
D) 6.4 × 10–5
E) 1.2 × 10–4
16) The solubility of magnesium fluoride in water at 18 °C is tabulated as 0.0076 g per 100 mL. What is the
solubility product for this salt?
A) 7.6 × 10–6
B) 6.8 × 10–7
C) 8.0 × 10–8
D) 7.3 × 10–9
E) 3.8 × 10-10
17) The solubility product constant of Li3PO4 is 3.2 × 10–9. What is the molar solubility of Li3PO4 in
water?
A) 3.3 × 10-3 M
B) 9.3 × 10-4 M
C) 7.5 × 10-3 M
D) 1.5 × 10-3 M
E) 5.7 × 10-5 M
18) The solubility of a salt MX2 with a molar mass of 114 g/mol is 3.42 g/L. Calculate Ksp.
A) 2.70 × 10–5
B) 1.08 × 10–4
C) 9.00 × 10–4
D) 2.25 × 10–4
E) 6.75 × 10–8
19) The solubility of cerium iodate, Ce(IO3)3, molar mass = 664.83 g/mol, in pure water is 124 mg per 100
mL of water. Calculate the solubility product constant for cerium iodate.
A) 4.9 × 10-19
B) 2.6 × 10-14
C) 8.6 × 10-15
D) 3.3 × 10–10
E) 3.5 × 10-18
20) A saturated solution of silver iodide has a concentration of 9.1 × 10-9 M. What is Ksp of this
compound?
A) 9.1 × 10-18
B) 9.1 × 10–3
C) 9.12 × 10–3
D) (2 × 9.2 × 10-3)2
E) (9.1 × 10-9)2
21) The solubility product constant of silver sulfate is 1.6 × 10-5. What is the molar solubility of this
compound?
A) 1.6 × 10–5 M
B) (16/2)1/2 × 10–2 M
C) (16/4)1/3 × 10–2 M
D) (16)1/2 × 10–3 M
E) (16/4)2/3 × 10–2 M
22) A saturated solution of silver chromate has a concentration of 7.4 × 10-5 M. What is Ksp of this
compound?
A) (7.4 × 10-5)2
B) (7.4 × 10-5)3
C) 3(7.4 × 10-5)3
D) 7.4 × 10–5
E) 4(7.4 × 10-5)3
23) The solubility product constant of silver bromide is 5.0 × 10–13. What is the molar solubility of this
compound?
A) 5.0 × 10-13 M
B) (50)1/2 × 10–6 M
C) (50)1/2 × 10–7 M
D) (5.0/2)1/2 × 10–7 M
E) (5.0 × 10–13)2 M
24) The solubility of a salt MX2 with a molar mass of 170 g/mol is 12.7 g/L. Calculate the Ksp.
A) 4.17 × 10–4
B) 5.58 × 10–3
C) 9.59 × 103
D) 2.23 × 10–2
E) 1.67 × 10–3
25) Which of the following salts, each of which has a solubility product equal to 1.0 × 10-6, has the
greatest molar solubility?
A) MX
B) MX2
C) MX3
D) M2X
26) Which of the following has the largest molar solubility?
A) BaSO4, Ksp = 1.1 × 10-10
B) AgCl, Ksp = 1.6 × 10-10
C) Mg(OH)2, Ksp = 2 × 10–11
D) Cr(OH)2, Ksp = 6.3 × 10-11
E) Fe(OH)3, Ksp = 4 × 10–38
27) Which of the following is least soluble?
A) NiS (Ksp = 8 × 10–37)
B) MnS (Ksp = 8 × 10–16)
C) PtS (Ksp = 8 × 10–73)
D) FeS (Ksp = 4 × 10–19)
E) Hg2Cl2 (Ksp = 1.3 × 10–18)
28) When solid silver chloride is shaken with a 0.1 molar aqueous solution of potassium iodide, most of
the silver chloride is converted to silver iodide. This transformation takes place because:
A) silver iodide is less soluble than silver chloride
B) I– is a better reducing agent than Cl–
C) I– has a larger radius than Cl–
D) the Ksp of AgI is larger than the Ksp of AgCl
E) potassium chloride precipitates
29) Which of the following is most soluble?
A) CuS (Ksp = 8 × 10–37)
B) Bi2S3 (Ksp = 1 × 10–70)
C) Ag2S (Ksp = 6 × 10–51)
D) MnS (Ksp = 7 × 10–16)
E) PbS (Ksp = 3 × 10–28)
30) Which of the following should dissolve the smallest amount of silver sulfide per liter, assuming no
complex formation?
A) 0.1 M HNO3
B) 0.1 M Na2S
C) 0.1 M AgNO3
D) 0.10 M NaNO3
E) pure water
31) Which of the following soil additives would best reduce the concentration of dissolved Fe3+ in
ground water?
A) lime [Ca(OH)2]
B) saltpeter [KNO3]
C) ferric chloride [FeCl3]
D) ammonium nitrate
E) ammonium sulfate
32) The solubility product constant of M2CrO4(s) is 7.11 × 10–15. How many moles of M2CrO4(s) will
dissolve in 744 mL of aqueous solution in which [CrO42-] = 0.056 M?
A) 2.7 × 10-7 mol
B) 1.8 × 10-7 mol
C) 1.2 × 10-5 mol
D) 9.0 × 10-5 mol
E) 3.6 × 10-7 mol
33) Predict the molar solubility of the following salt in an aqueous solution that contains the given
concentration of one of its ions:
BaSO4; [SO42-] = 4.3 × 10-5 M; Ksp = 1.1 × 10-10
A) 4.7 × 10–15 M
B) 6.9 × 10-8 M
C) 8.0 × 10-4 M
D) 2.6 × 10-6 M
E) 1.6 × 10-3 M
34) Predict the molar solubility of the following salt in an aqueous solution that contains the given
concentration of one of its ions:
AgI; [I–] = 7.2 × 10-6 M; Ksp = 8.5 × 10-17
A) 2.4 × 10-11 M
B) 9.2 × 10–9 M
C) 1.7 × 10–6 M
D) 2.7 × 10–4 M
E) 1.2 × 10-11 M
35) What is the molar solubility of PbI2 (Ksp = 7.1 × 10-9) in 0.10 M Pb(NO3)2(aq)?
A) 1.3 × 10-4 M
B) 2.6 × 10-3 M
C) 7.1 × 10-8 M
D) 2.7 × 10-4 M
E) 2.7 × 10-5 M
36) The Ksp of AgCl is 1.7 × 10–10. How many moles of MnCl2 can be dissolved in one liter of an aqueous
solution in which [AgNO3] = 3.4 × 10-4 M before a precipitate appears?
A) 5.0 × 10-7 mol
B) 5.8 × 10–14 mol
C) 2.4 × 10-7 mol
D) 2.0 × 106 mol
E) 2.5 × 10-7 mol
37) The solubility product constant for iron(III) hydroxide at 22 °C is 6.0 × 10–38. What mass of this
compound will dissolve in 100 mL of 0.20 M aqueous sodium hydroxide, assuming no complex
formation?
A) 6 × 10–39 g
B) 7 × 10–37 g
C) 8 × 10–35 g
D) 9 × 10–33 g
E) 1 × 10–30 g
38) Which of the following reduces the solubility of calcium fluoride?
A) presence of “uncommon ions” such as Na+ and Cl–
B) formation of the ion-pair CaF+
C) formation of the complex ion CaF42-
D) decreasing the pH
E) cooling the solution
39) Fe(OH)3 is most soluble in which aqueous solution?
A) 0.2 M HCl
B) 0.1 M KOH
C) pure water
D) 0.1 M FeCl3
E) 0.2 M CaCl2
40) When equal volumes of the indicated aqueous solutions are mixed, precipitation should occur only
for:
barium fluoride 1.0 × 10–6
calcium carbonate 2.8 × 10–9
calcium fluoride 5.3 × 10-9
magnesium fluoride 3.7 × 10-8
silver carbonate 8.5 × 10-12
A) 2 × 10-5 M Ag+ + 2 × 10–5 M CO32-
B) 2 × 10-5 M Ca2+ + 2 × 10-5 M CO32-
C) 2 × 10-4 M Ca2+ + 2 × 10-2 M F–
D) 2 × 10-5 M Mg2+ + 2 × 10-6 M F–
E) 2 × 10-3 M Ba2+ + 2 × 10-3 M F–
41) When equal volumes of the indicated aqueous solutions are mixed, precipitation should occur only
for:
barium fluoride 1.0 × 10–6
calcium carbonate 2.8 × 10–9
calcium fluoride 5.3 × 10-9
magnesium fluoride 3.7 × 10-9
silver carbonate 8.5 × 10-12
A) 2 × 10-5 M Ag+ + 2 × 10–5 M CO32-
B) 2 × 10-4 M Ca2+ + 2 × 10-4 M CO32-
C) 2 × 10-5 M Ca2+ + 2 × 10-3 M F–
D) 2 × 10-5 M Mg2+ + 2 × 10-6 M F–
E) 2 × 10-3 M Ba2+ + 2 × 10-3 M F–
42) When equal volumes of the indicated aqueous solutions are mixed, precipitation should occur only
for:
barium fluoride 1.0 × 10–6
calcium carbonate 2.8 × 10–9
calcium fluoride 5.3 × 10-9
magnesium fluoride 3.7 × 10-8
silver carbonate 8.5 × 10-12
A) 2 × 10-5 M Ag+ + 2 × 10–5 M CO32-
B) 2 × 10-5 M Ca2+ + 2 × 10-5 M CO32-
C) 2 × 10-5 M Ca2+ + 2 × 10-3 M F–
D) 2 × 10-2 M Mg2+ + 2 × 10-3 M F–
E) 2 × 10-3 M Ba2+ + 2 × 10-3 M F–
43) A homeowner in Boston becomes concerned that there may be appreciable amounts of lead in her
drinking water due to 150-year old water pipes in her house. Consequently, she takes a sample of her
drinking water in to be analyzed. The laboratory technician, who is new on the job, has been told to
analyze by precipitating the lead ion as the iodide (Ksp = 7.1 × 10-9 for PbI2(s)) by slowly adding small
portions of 1.00 M NaI(aq) solution.
If we assume that the concentration of lead in the solution is 1.00 mg/liter or approximately 4.8 × 10-6 M
(this would be 1.0 part per million) is it possible to detect the lead in the drinking water by adding a total
of no more than 10.0 mL of NaI(aq) solution to a 100 mL sample of drinking water? You must of course
consider dilution effects. What is Qsp?
A) yes, Qsp = 4.0 × 10–7
B) yes, Qsp = 3.6 × 10–8
C) no, Qsp = 1.6 × 10-13
D) no, Qsp = 3.6 × 10–8
E) no, Qsp = 4.0 × 10–7
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44) When 100 mL each of 2.0 × 10-4 M Ca2+(aq) and 2.0 × 10-2 M F–(aq) are mixed, what is the remaining
Ca2+(aq) ion concentration and is precipitation complete? The solubility product constant of CaF2(s) is
5.3 × 10-9.
A) 5.6 × 10–4 M, no
B) 1.7 × 10–8 M, yes
C) 4.3 × 10–7 M, no
D) 1.7 × 10–6 M, yes
E) 5.3 × 10–5 M, no
45) When 100 mL each of 2.0 × 10-5 M Ca2+(aq) and 2.0 × 10-3 M CO32-(aq) are mixed, what is the
remaining Ca2+(aq) ion concentration and is precipitation complete? The solubility product constant of
CaCO3(s) is 2.8 × 10-9.
A) 2.8 × 10–6 M, no
B) 1.0 × 10–3 M, no
C) 6.9 × 10–5 M, no
D) 2.8 × 10–3 M, no
E) 2.8 × 10–6 M, yes
46) When 100 mL each of 2.0 × 10-6 M Ag+(aq) and 2.0 × 10-3 M Br–(aq) are mixed, what is the remaining
Ag+(aq) ion concentration and is precipitation complete? The solubility product constant of AgBr(s) is 5.0
× 10–13.
A) 7.1 × 10–7 M, no
B) 5.0 × 10-10 M, yes
C) 1.0 × 10–3 M, no
D) 5.0 × 10–13 M, yes
E) 2.5 × 10-10 M, yes
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47) When 100 mL each of 2.0 × 10-4 M Ag+(aq) and 2.0 × 10-1 M CO32-(aq) are mixed, what is the
remaining Ag+(aq) ion concentration and is precipitation complete? The solubility product constant of
Ag2CO3(s) is 8.5 × 10–12.
A) 4.2 × 10–8 M, yes
B) 2.0 × 10–4 M, no
C) 9.2 × 10–6 M, no
D) 1.0 × 10–3 M, no
E) 8.5 × 10–9 M, yes
48) Consider an aqueous solution which is 0.020 M in Pb2+ and 0.20 M in Ag+. Concentrated aqueous
potassium iodide solution (so that volume changes may be neglected) is added gradually with good
stirring to this solution. Eventually the iodide ion concentration should increase enough to cause
precipitation of the second ion. What will be the concentration of the ion that precipitates first when the
second ion just begins to precipitate?
A) 2.0 × 10–17 M
B) 1.2 × 10-8 M
C) 5.0 × 10–20 M
D) 1.4 × 10–13 M
E) 1.2 × 10-5 M
49) An aqueous solution contains [Ba2+] = 5.0 × 10-5 M, [Ag+] = 3.0 × 10-5 M, and [Zn2+] = 2.0 × 10-7 M.
Sodium oxalate is slowly added so that [C2O42-] increases.
Salt BaC2O4 ZnC2O4 Ag2C2O4
Ksp 1.5 × 10-8 1.35 × 10-9 1.1 × 10–11
What is the concentration of the first cation to precipitate when the second cation just begins to
precipitate?
A) 1.3 × 10–6 M
B) 2.2 × 10–6 M
C) 5.0 × 10–5 M
D) 1.35 × 10–9 M
E) 1.1 × 10-11 M
50) To a saturated aqueous solution of barium carbonate is added just enough sodium sulfate to achieve a
maximum sulfate concentration without precipitation of barium sulfate. If no complexes form and the
“salt effect” is negligible, what is the concentration of the sulfate ion in this solution? [Ksp for barium
carbonate is 1.6 × 10-9; Ksp for barium sulfate is 7.9 × 10–11]
A) 2.8 × 10-5 M
B) 6.7 × 10-6 M
C) 2.0 × 10-6 M
D) 4.0 × 10-5 M
E) 8.9 × 10-5 M
51) In which of the following one molar aqueous solutions would you expect cadmium sulfide, CdS, to be
the most soluble?
A) NaCl
B) HCl
C) NaOH
D) C2H5OH
E) KOH
52) The solubility product constant of Mg(OH)2 is 9.0 × 10–12. If an aqueous solution is 0.010 M with
respect to Mg2+ ion, the amount of [OH–] required to start the precipitation of Mg(OH)2(s) is:
A) 1.5 × 10–7 M
B) 3.0 × 10-5 M
C) 3.0 × 10-7 M
D) 9.0 × 10–10 M
E) 1.5 × 10-5 M
53) To a concentrated buffer of pH 9.0 was added an equal volume of an aqueous solution that was 0.20
M in each of the ions Ca2+, Cd2+, and Cu2+. The expected precipitate would consist of:
salt: calcium hydroxide cadmium hydroxide copper(II) hydroxide
Ksp: 4.0 × 10-6 2.0 × 10–14 1.8 × 10-19
A) only Ca(OH)2
B) only Cd(OH)2
C) only Cu(OH)2
D) only Cd(OH)2 and Cu(OH)2
E) Ca(OH)2, Cd(OH)2, and Cu(OH)2
54) If iron(III) acetate is added to be 1 × 10–10 M in an aqueous solution that is 0.10 M NH3, what is Qsp
and will Fe(OH)3 precipitate? The Ksp of Fe(OH)3(s) is 4 × 10–38 and Kb for NH3 is 1.8 × 10–5.
A) 1.3 × 10–13, yes
B) 1.7 × 10–16, yes
C) 1.7 × 10–16, no
D) 2.4 × 10–19, yes
E) 2.4 × 10–19, no
55) If chromium(III) chloride is added to be 1 × 10–12 M in an aqueous solution that is 0.10 M NH3, what
is Qsp and will Cr(OH)3(s) precipitate? The Ksp of Cr(OH)3 is 6.3 × 10–31 and Kb for NH3 is 1.8 × 10–5.
A) 1.0 × 10–16, yes
B) 2.4 × 10–23, no
C) 2.2 × 10–19, no
D) 2.2 × 10–19, yes
E) 2.4 × 10–21, yes