54. Determine the ion product.
A)
1.1 10–4
B)
1.5 10–2
C)
7.8 10–3
D)
8.1 10–4
E)
none of these
55. Will precipitation occur?
A)
Yes.
B)
No.
C)
Maybe, it depends on the temperature.
D)
Maybe, it depends on the limiting reagent concentration.
E)
None of these.
56. What is the limiting reagent in the formation of the lead chloride?
A)
Pb2+
B)
Cl–
C)
(NO3)–
D)
PbCl2
E)
Pb(NO3)2
57. Determine the equilibrium concentration of the chloride ion.
A)
3.9 10–4
B)
8.0 10–6
C)
2.8 10–3
D)
6.1 10–2
E)
none of these
58. The Ksp for BaF2 is 2.4 10–5. When 10 mL of 0.01 M NaF is mixed with 10 mL of 0.01 M
BaNO3, will a precipitate form?
A)
No, because Q is 1 10–12 and since it is less than Ksp no precipitate will form.
B)
Yes, because Q is 1 10–12 and since it is less than Ksp a precipitate will form.
C)
No, because Q is 1.25 10–7 and since it is less than Ksp no precipitate will form.
D)
Yes, because Q is 1.25 10–7 and since it is less than Ksp a precipitate will form.
E)
None of the above.
59. How many moles of Ca(NO3)2 must be added to 1.0 L of a 0.182 M KF solution to begin
precipitation of CaF2? For CaF2, Ksp = 4.0 10–11.
A)
6.0 10−10
B)
2.2 10−10
C)
1.3 10−12
D)
1.2 10−9
E)
3.5 10−5
60. A 50.0-mL sample of 0.100 M Ca(NO3)2 is mixed with 50.00 mL of 0.200 M NaF. When
the system has come to equilibrium, which of the following sets of conditions will hold?
The Ksp for CaF2 is 4.0 10–11.
Moles Solid CaF2
Formed
[Ca2+]
[F–]
A)
B)
C)
D)
E)
61. The Ksp for Mn(OH)2 is 2.0 10–13. At what pH will Mn(OH)2 begin to precipitate from a
solution in which the initial concentration of Mn2+ is 0.10 M?
A)
6.47
B)
13.3
C)
5.85
D)
7.03
E)
8.15
62. Sodium chloride is added slowly to a solution that is 0.010 M in Cu+, Ag+, and Au+. The Ksp
values for the chloride salts are 1.9 10–7, 1.6 10–10, and 2.0 10–13, respectively. Which
compound will precipitate first?
A)
CuCl
B)
AgCl
C)
AuCl
D)
All will precipitate at the same time.
E)
Cannot be determined.
63. A 0.012-mol sample of Na2SO4 is added to 400 mL of each of two solutions. One solution
contains 1.5 10–3 M BaCl2; the other contains 1.5 10–3 M CaCl2. Given that Ksp for
BaSO4 = 1.5 10–9 and Ksp for CaSO4 = 6.1 10–5:
A)
BaSO4 would precipitate but CaSO4 would not.
B)
CaSO4 would precipitate but BaSO4 would not.
C)
Both BaSO4 and CaSO4 would precipitate.
D)
Neither BaSO4 nor CaSO4 would precipitate.
E)
Not enough information is given to determine if precipitation would occur.
64. If 30 mL of 5.0 10–4 M Ca(NO3)2 are added to 70 mL of 2.0 10–4 M NaF, will a
precipitate occur? (Ksp of CaF2 = 4.0 10–11)
A)
No, because the ion product is greater than Ksp.
B)
Yes, because the ion product is less than Ksp.
C)
No, because the ion product is less than Ksp.
D)
Not enough information is given.
E)
Yes, because the ion product is greater than Ksp.
65. The concentration of Mg2+ in seawater is 0.052 M. At what pH will 99% of the Mg2+ be
precipitated as the hydroxide? [Ksp for Mg(OH)2 = 8.9 10–12]
A)
8.35
B)
9.22
C)
6.50
D)
10.12
E)
4.86
66. A precipitate forms when a solution that is 0.10 M in Cu2+, Pb2+, and Ni2+ is saturated with
H2S and adjusted to pH = 1. What sulfides are present in the precipitate?
[H2S] = 0.10 M; for H2S, Ka1 Ka2 = 1.1 10–24
Ksp: CuS = 8.5 10–45, PbS = 7.0 10–29, NiS = 3.0 10–21
A)
CuS, PbS, and NiS
B)
PbS and NiS
C)
NiS
D)
CuS and PbS
E)
CuS
67. A solution is 0.010 M in each of Pb(NO3)2, Mn(NO3)2, and Zn(NO3)2. Solid NaOH is added
until the pH of the solution is 8.50. Which of the following statements is true?
Salt
Ksp
Pb(OH)2
1.4 10–20
Mn(OH)2
2.0 10–13
Zn(OH)2
2.1 10–16
A)
No precipitate will form.
B)
Only Pb(OH)2 will precipitate.
C)
Only Mn(OH)2 will precipitate.
D)
Only Zn(OH)2 and Pb(OH)2 will precipitate.
E)
All three hydroxides will precipitate.
68. An industrial plant processes its waste water through a sedimentation tank that removes
hazardous metals by precipitating them as insoluble carbonate salts. If sodium carbonate is
gradually added to the tank, what would be the order of precipitation of the metals, Pb2+,
Cu2+, Hg22+, and Zn2+ if each is 1.0 10–4 M? ( Ksp PbCO3 = 7.4 10–14, Ksp
CuCO3 = 1.4 10–10, Ksp Hg2CO3 = 8.9 10–17, and Ksp ZnCO3 = 1.4 10–11)
A)
Pb2+, Hg22+, Zn2+, Cu2+
B)
Hg22+, Pb2+, Zn2+, Cu2+
C)
Cu2+, Zn2+, Pb2+, Hg22+
D)
Cu2+, Zn2+, Hg22+, Pb2+
E)
All metal ions will precipitate at the same time.
69. A solution contains 0.018 moles each of I–, Br–, and Cl–. When the solution is mixed with
200 mL of 0.24 M AgNO3, how much AgCl(s) precipitates out?
Ksp
AgI
= 1.5 10–16
Ksp
AgBr
= 5.0 10–13
Ksp
AgCl
= 1.6 10–10
A)
0.0 g
B)
1.7 g
C)
2.6 g
D)
3.3 g
E)
5.0 g
70. A 100.-mL sample of solution contains 10.0 mmol of Ca2+ ion. How many mmol of solid
Na2SO4 must be added in order to cause precipitation of 99.9% of the calcium as CaSO4?
The Ksp of CaSO4 is 6.1 10–5. Assume the volume remains constant.
A)
17.4
B)
10.0
C)
61.0
D)
71.0
E)
6.1
71. What is the maximum concentration of carbonate ions that will precipitate BaCO3 but not
MgCO3 from a solution that is
1.9 10−3
M each in Mg2+ and Ba2+? For MgCO3,
Ksp = 1.0 10–15 and for BaCO3, Ksp = 2.6 10–9.
A)
5.3 10−13
M
B)
1.4 10−6
M
C)
3.2 10−8
M
D)
5.1 10−5
M
E)
None of these; MgCO3 will always precipitate before BaCO3.
72. What is the maximum concentration of iodide ions that will precipitate AgI but not PbI2
from a solution that is
1.5 10−3
M each in Ag+ and Pb2+? For AgI, Ksp = 1.5 10–16 and for
PbI2, Ksp = 1.4 10–8.
A)
3.1 10−3
M
B)
1.0 10−13
M
C)
9.3 10−6
M
D)
1.2 10−8
M
E)
None of these; PbI2 will always precipitate before AgI.
73. In the qualitative analysis scheme for metal ions, how are the Analytical Group I cations
separated from the other cations?
A)
by addition of HCl, forming insoluble metal chlorides
B)
by addition of H2SO4, forming insoluble metal sulfates
C)
by addition of H2S in acidic solution, forming insoluble metal sulfides
D)
by addition of H2S in basic solution, forming insoluble metal sulfides or
hydroxides
E)
by addition of (NH4)2CO3 or (NH4)3PO4, forming insoluble metal carbonates or
phosphates
74. In the qualitative analysis scheme for metal ions, how are the Analytical Group II cations
separated from the cations of Analytical Groups III–V?
A)
by addition of HCl, forming insoluble metal chlorides
B)
by addition of H2SO4, forming insoluble metal sulfates
C)
by addition of H2S in acidic solution, forming insoluble metal sulfides
D)
by addition of H2S in basic solution, forming insoluble metal sulfides or
hydroxides
E)
by addition of (NH4)2CO3 or (NH4)3PO4, forming insoluble metal carbonates or
phosphates
75. In the qualitative analysis scheme for metal ions, how are the Analytical Group III cations
separated from the cations of Analytical Groups IV and V?
A)
by addition of HCl, forming insoluble metal chlorides
B)
by addition of H2SO4, forming insoluble metal sulfates
C)
by addition of H2S in acidic solution, forming insoluble metal sulfides
D)
by addition of H2S in basic solution, forming insoluble metal sulfides or
hydroxides
E)
by addition of (NH4)2CO3 or (NH4)3PO4, forming insoluble metal carbonates or
phosphates
76. When a mixture containing cations of Analytical Groups I–III is treated with H2S in acidic
solution, which cations are expected to precipitate?
A)
Analytical Group I only
B)
Analytical Group II only
C)
Analytical Group III only
D)
Analytical Groups I and II
E)
Analytical Groups II and III
77. In the classic scheme for qualitative analysis, the cations of Analytical Group IV are
precipitated as phosphates or carbonates. Analytical Group IV consists of
A)
alkali metals
B)
alkaline earth elements
C)
the halogens
D)
transition metals having +2 ions
E)
none of these
78. Consider a solution containing the following cations: Na+, Hg2+, Mn2+, Al3+ and Ag+.
Treatment of the solution with dilute HCl followed by saturation with H2S results in
formation of precipitate(s). Which ions still remain in solution (i.e., did not precipitate)?
A)
Ag+ only
B)
Na+, Hg2+, Al3+
C)
Ag+ and Hg2+
D)
Na+, Al3+, and Mn2+
E)
Na+ only
79. Which of the following solid salts should be more soluble in 1.0 M NH3 than in water?
A)
Na2CO3
B)
KCl
C)
AgBr
D)
KNO3
E)
none of these
80. The overall Kf for the complex ion Ag(NH3)2+ is 1.7 107. The Ksp for AgI is 1.5 10–16.
What is the molar solubility of AgI in a solution that is 2.0 M in NH3?
A)
1.5 10–9
B)
1.3 10–3
C)
1.0 10–4
D)
5.8 10–12
E)
8.4 10–5
81. The Kf for the complex ion Ag(NH3)2+ is 1.7 107. The Ksp for AgCl is 1.6 10–10.
Calculate the molar solubility of AgCl in 1.0 M NH3.
A)
5.2 10–2
B)
4.7 10–2
C)
2.9 10–3
D)
1.3 10–5
E)
1.7 10–10
82. Given the following values of equilibrium constants:
Cu(OH)2(s)Cu2+(aq) + 2OH–(aq)
Ksp = 1.60 10–19
Cu(NH3)42+(aq)Cu2+(aq) + 4NH3(aq)
K = 1.0 10–13
What is the value of the equilibrium constant for the following reaction?
Cu(OH)2(s) + 4NH3(aq) Cu(NH3)42+(aq) + 2OH–(aq)
A)
1.60 10−19
B)
1.6 10−32
C)
1.6 10−6
D)
6.25 1018
E)
1.0 1013
Consider a solution made by mixing 500.0 mL of 4.0 M NH3 and 500.0 mL of 0.40 M
AgNO3. Ag+ reacts with NH3 to form AgNH3+ and Ag(NH3)2+:
Ag+ + NH3AgNH3+
K1 = 2.1 103
AgNH3+ + NH3Ag(NH3)2+
K2 = 8.2 103
83. The concentration of Ag(NH3)2+ at equilibrium is:
A)
2.0 M
B)
0.40 M
C)
0.20 M
D)
1.0 10–3 M
E)
none of these
formation | equilibrium calculations with Kf MSC: Quantitative
84. The concentration of Ag+ at equilibrium is:
A)
2.0 M
B)
1.2 10–8 M
C)
4.5 10–9 M
D)
1.6 M
E)
none of these
The following questions refer to the following system: 500.0 mL of 0.020 M Mn(NO3)2 are
mixed with 1.0 L of 1.0 M Na2C2O4. The oxalate ion, C2O4, acts as a ligand to form a
complex ion with the Mn2+ ion with a coordination number of two.
Mn2+ + C2O42–MnC2O4
K1 = 7.9 103
[Mn(C2O4)2]2–MnC2O4 + C2O42–
K2 = 1.26 10–2
85. What is the equilibrium constant for the following formation?
Mn2+ + 2C2O42–[Mn(C2O4)2]2–
A)
1.0
B)
3.7 102
C)
2.1 10–1
D)
6.3 105
E)
none of these
86. Find the equilibrium concentration of the [Mn(C2O4)2]2– ion.
A)
9.2 10–5 M
B)
0.01 M
C)
2.5 10–8 M
D)
1.3 10–4 M
E)
6.7 10–3 M
87. Find the equilibrium concentration of Mn(C2O4) in the system.
A)
9.2 10–5 M
B)
0.01 M
C)
2.5 10–8 M
D)
1.3 10–4 M
E)
6.7 10–3 M
KEY: Chemistry | general chemistry | solubility | complex ion equilibria | complex ion
formation | equilibrium calculations with Kf MSC: Quantitative
88. Find the equilibrium concentration of the Mn2+ ion.
A)
9.2 10–5 M
B)
0.01 M
C)
2.5 10–8 M
D)
1.3 10–4 M
E)
6.7 10–3 M
89. Silver acetate, AgC2H3O2, is a sparingly soluble salt with Ksp = 1.9 10–3. Consider a
saturated solution in equilibrium with the solid salt. Compare the effects on the solubility of
adding to the solution either the acid HNO3 or the base NH3.
A)
Either substance would decrease the solubility.
B)
NH3 would increase the solubility, but HNO3 would decrease it.
C)
NH3 would increase the solubility, but HNO3 would have virtually no effect.
D)
Either substance would increase the solubility.
E)
NH3 would decrease the solubility, but HNO3 would increase it.
90. Calculate the molar concentration of uncomplexed Zn2+ in a solution that contains 0.20 mole
of Zn(NH3)42+ per liter and 0.0116 M NH3 at equilibrium. The overall Kf for Zn(NH3)42+ is
3.8 109.
A)
2.9 10–3 M
B)
8.8 10–3 M
C)
6.7 10–4 M
D)
2.0 10–13 M
E)
none of these
91. The cation M2+ reacts with NH3 to form a series of complex ions as follows:
M2+ + NH3M(NH3)2+
K1 = 102
M(NH3)2+ + NH3M(NH3)22+
K2 = 103
M(NH3)22+ + NH3M(NH3)32+
K3 = 102
A 1.0 10–3 mol sample of M(NO3)2 is added to 1.0 L of 15.0 M NH3 (Kb = 1.8 10–5).
Choose the dominant species in this solution.
A)
M2+
B)
M(NH3)2+
C)
M(NH3)22+
D)
M(NH3)32+
E)
M(NO3)2
92. What is the molar solubility of lead(II) chromate in 0.055 M Na2S2O3? For PbCrO4,
Ksp = 2.0 10–16; for Pb(S2O3)34–, Kf = 2.2 106.
A)
2.7 10−7
M
B)
4.9 10−6
M
C)
4.4 10−10
M
D)
6.1 102
M
E)
1.7 10−4
M
93. Consider the following three complex ions of Ag+ and their formation constants, Kf.
Ag(NH3)2+ Kf = 1.7 107
Ag(CN)2– Kf = 5.6 1018
AgBr2– Kf = 1.0 1011
Which of the following responses are true?
1. Ag(NH3)2+ is more stable than Ag(CN)2–.
2. Adding a strong acid (HNO3) to a solution that is 0.010 M in Ag(NH3)2+ would tend to
dissociate the complex ion.
3. Adding a strong acid (HNO3) to a solution that is 0.010 M in AgBr2– would tend to
dissociate the complex ion.
4. To dissolve AgI add either NaCN or HCN, fewer moles of NaCN would be required.
A)
1 and 2
B)
1 and 3
C)
1 and 4
D)
2 and 4
E)
2 and 3
94. What is the concentration of Ni2+(aq) ion in a 0.045 M Ni(NO3)2 solution that is also 1.0 M
NH3? [Kf for Ni(NH3)62+ = 5.5 108]
A)
5.4 10−10
M
B)
1.1 10−10
M
C)
8.2 10−11
M
D)
4.5 10−2
M
E)
none of these
95. What is the concentration of the Cd2+(aq) ion in a 0.030 M Cd(NO3)2 solution that is also
1.0 M NH3? At this temperature, Kf for Cd(NH3)42+ = 1.0 107.
A)
3.0 10−9
M
B)
5.0 10−9
M
C)
3.0 10−30
M
D)
1.0 10−7
M
E)
none of these