Chapter 3 - Solubility
Practice Test #1
6. The equation that represents the equilibrium in a saturated solution of Fe2(SO4)3 is
A.
Fe2(SO4)3(s) ⇄ 3Fe2+(aq) + 2SO43-(aq)
B.
Fe2(SO4)3(s) ⇄ 2Fe2+(aq) + 3SO43-(aq)
C.
Fe2(SO4)3(s) ⇄ 3Fe3+(aq) + 2SO42-(aq)
D.
Fe2(SO4)3(s) ⇄ 2Fe3+(aq) + 3SO42-(aq)
7. When equal volumes of 0.20 M K2CrO4 and 0.20 M AgNO3 are mixed, a red precipitate is formed. The
net ionic equation for this reaction is
A.
B.
C.
D.
K+(aq) + NO3-(aq) → KNO3(s)
2Ag+(aq) + CrO42-(aq) → Ag2CrO4(s)
K2CrO4(aq) + 2AgNO3(aq) → Ag2CrO4(s) + 2KNO3(aq)
2Ag+(aq) + CrO4-(aq) + 2K+(aq) + 2NO3-(aq) → Ag2CrO4(s) + 2KNO3(s)
8. Which of the following compounds could be used to prepare a 0.20 M solution of hydroxide ion?
A.
KOH
B.
Fe(OH)3
C.
Mg(OH)2
D.
Zn(OH)2
9. When 250 mL of 0.36 M Sr(OH)2 are added to 750 mL of water, the resulting ion concentrations are
A.
B.
C.
D.
[Sr2+]
[Sr2+]
[Sr2+]
[Sr2+]
= 0.12 M and [OH-]
= 0.12 M and [OH-]
= 0.090 M and [OH-]
= 0.090 M and [OH-]
=
=
=
=
0.12 M
0.24 M
0.090 M
0.180 M
10. When equal volumes of 2.0 M Pb(NO3)2 and 2.0 M KCl are mixed,
A.
B.
C.
D.
a precipitate forms because the trial ion product < Ksp
a precipitate forms because the trial ion product > Ksp
a precipitate does not form because the trial ion product < Ksp
a precipitate does not form because the trial ion product > Ksp
11. Consider the following equilibrium: AgCl(s) ⇄ Ag+(aq) + Cl-(aq)
When Br-(aq) is added to a saturated solution of AgCl,
A.
more AgCl dissolves and its solubility product increases.
B.
more AgCl precipitates and its solubility product decreases.
C.
more AgCl dissolves and its solubility product remains constant.
D.
more AgCl precipitates and its solubility product remains constant.
1
12. The molar solubility of iron II sulphide is
A.
B.
3.6 x 10-37 M
3.0 x 10-19 M
6.0 x 10-19 M
7.7 x 10-10 M
C.
D.
13. A solution containing an unknown cation was added to three solutions and the following observations
were recorded:
Solution
Observation
NaI
no precipitate
Na2SO4
precipitate
NaOH
no precipitate
The unknown cation is
A.
Pb2+
B.
Sr2+
C.
Ca2+
D.
Ag+
14. If the solubility of Pb(OH)2 is 0.155 g/L, then the concentration of each ion in a saturated solution is
A.
B.
C.
D.
[Pb2+]
[Pb2+]
[Pb2+]
[Pb2+]
=
=
=
=
0.155 g/L and [OH-] = 0.155 g/L
0.155 g/L and [OH-] = 0.103 g/L
6.43 x 10-4 M and [OH-] = 1.29 x 10-3 M
6.43 x 10-4 M and [OH-] = 6.43 x 10-3 M
15. Which of the following could be used to separate Pb2+ from Ba2+ by precipitation?
A.
Na2S
B.
NaOH
C.
Na2CO3
D.
Na2SO4
D.
K2SO4(s)
D.
Ba(OH)2
16. When dissolved in water, which of the following form a molecular solution?
A.
HCl(g)
B.
NaNO3(s)
C.
CH3OH(l)
17. Which of the following will be most soluble in water at 25 oC.
A.
AgI
B.
PbS
C.
MgSO4
18. At 25 oC, the solubility of Mg(OH)2 is
A.
B.
1. x 10-32 M
1. x 10-12 M
C.
D.
1. x 10-6 M
1. x 10-4 M
19. At 25 oC, the solubility of an unknown compound is 7.1 x 10-5 M. The compound is
A.
B.
CuI
AgI
C.
D.
CaCO3
CaSO4
2
20. When solid AgBr is added to a saturated solution of AgBr, the reaction rates can be described as:
Rate of Dissolving
Rate of Crystalizing
A.
B.
C.
D.
increasing
increasing
decreasing
increasing
increasing
decreasing
increasing
no change
21. The solubility of PbS is 2.9 x 10-14 M. What is the value of the Ksp.
A.
B.
8.4 x 10-28
2.9 x 10-14
C.
D.
5.8 x 10-14
1.7 x 10-7
22. Which of the following causes a precipitate to form when Sr2+(aq) is added but not when Zn2+(aq) is
added?
A.
B.
S2Cl-
C.
D.
SO42CO32-
23. A 3.0 L solution of NiCl2 is found to have a chloride concentration of 0.60 M. The concentration of
nickel II ions is
A.
B.
0.30 M
0.60 M
C.
D.
0.90 M
1.2 M
24. When equal volumes of 0.20 M K2CO3 and 0.2 M Na3PO4 are mixed,
A.
B.
C.
D.
no precipitate will form
a precipitate of K3PO4 will form
a precipitate of Na2CO3 will form
a precipitate of K3PO4 and Na2CO3 will form
25. A solution of AgNO3 is slowly added to a mixture containing 0.10 M I-, Cl-, Br-, and IO3-. The
precipitate which forms first is
A.
AgI
B.
AgCl
C.
AgBr
D.
AgIO3
26. Which of the following units can be used to represent solubility?
A.
B.
g
mol
C.
D.
mol/L
mL/s
27. Consider the following equilibrium: CaCO3(s) ⇄ Ca2+(aq) + CO32-(aq)
Which of the following reagents when added to the equilibrium system, would cause more CaCO3 to
dissolve?
A.
KNO3(s)
C.
H2C2O4(s)
B.
CaCO3(s)
D.
Na2CO3(s)
3
28. Which of the following could be used to precipitate both Mg2+ and Ca2+ from hard water?
A.
B.
lithium sulphate
sodium phosphate
C.
D.
potassium sulphide
ammonium chloride
29. What is the maximum [Ag+] that can exist in 0.20 M NaBrO3?
A.
B.
1.1 x 10-5 M
5.3 x 10-5 M
C.
D.
2.6 x 10-4 M
7.3 x 10-3 M
30. Which of the following ions could be used to separate Cl-(aq) from SO42-(aq) by precipitation?
A.
Ag+
B.
Ca2+
C.
NH4+
C.
D.
Ksp = [3Ca2+][2PO43-]
Ksp = [3Ca2+][2PO43-]
D.
Pb2+
31. The Ksp expression for a saturated solution Ca3(PO4)2 is
A.
B.
Ksp = [Ca2+][PO43-]
Ksp = [Ca2+]3[PO43-]2
32. When Ca(OH)2 attains solubility equilibrium, the
A.
B.
solution will be saturated
pH will be less than 7
C.
D.
trial Ksp is less than the Ksp
concentrations of the ions are equal
33. Which of the following describes the changes in ion concentrations when 1.0 g of solid ZnS is added
to a saturated solution of ZnS?
A.
B.
C.
D.
[Zn2+]
[S2-]
increases
decreases
increases
remains constant
decreases
decreases
increases
remains constant
34. The net ionic equation for the reaction between Sr(OH)2 and H2SO4 is
A.
H+ + OH- → H2O
B.
Sr2+ + SO42- → SrSO4
C.
Sr(OH)2 + H2SO4 → SrSO4 + 2H2O
D.
Sr2+ + 2OH- + 2H+ + SO42- → SrSO4 + 2H2O
35. The relationship between the solubility and the size of the Ksp is
A.
B.
C.
D.
there is no relationship
the smaller the Ksp the greater the solubility
the greater the Ksp the greater the solubility
the solubility is always the square root of the Ksp
4
36. Which of the following compounds will form a saturated solution with the greatest concentration of
Ag+?
A.
B.
AgI
AgBr
C.
D.
AgIO3
AgBrO3
37. When equal volumes of 0.20 M CuSO4 and 0.20 M Li2S are combined, the complete ionic equation is
A.
B.
C.
D.
Cu2+(aq) +
CuSO4(aq)
Cu2+(aq) +
Cu2+(aq) +
S2-(aq) → CuS(s)
+ Li2S(aq) → CuS(s) + Li2SO4(aq)
SO42-(aq) + 2Li+(aq) + S2-(aq) → CuS(s) + Li2SO4(aq)
SO42-(aq) + 2Li+(aq) + S2-(aq) → CuS(s) + 2Li+(aq) + SO42-(aq)
38. Which of the following would have the [Fe3+] = 0.020 M?
A.
B.
0.40 L of 0.050 M Fe(NO3)3
0.80 L of 0.020 M Fe2(SO4)3
C.
D.
0.50 L of 0.040 M FeC6H5O7
0.50 L of 0.010 M Fe2(C2O4)3
39. A solution contains both Ag+ and Mg2+ ions. During selective precipitation, these ions are removed
one at a time by adding
A.
B.
I- followed by OHOH- followed by S2-
C.
D.
SO42- followed by ClNO3- followed by PO43-
C.
D.
Cu(IO3)2
Mg(OH)2
40. The solubility of an AB2 type salt is 2.3 x 10-6 M. The salt is
A.
B.
PbBr2
Fe(OH)2
1. A saturated solution of BaSO4 is given to patients needing digestive tract x-rays.
a) Write an equation that represents the solubility equilibrium
b) Calculate the [Ba2+] present in the saturated solution.
2. Will a precipitate form when 90.0 mL of 1.00 x 10-2 M Cu(NO3)2 and 10.0 mL of 1.00 x 10-2 M NaIO3
are mixed? Explain using appropriate calculations.
5
3. What is the maximum [CO32-] that can exist in a 1.3 x 10-4 M AgNO3 solution?
4. The following data was collected when a 25.00 mL sample of water containing chloride ion was
titrated using 0.100 M AgNO3 to completely precipitate the chloride ion.
Initial volume of AgNO3
Final volume of AgNO3
18.30 mL
27.22 mL
a) Write the net ionic reaction for the precipitation reaction.
c) Calculate the [Cl-].
5. In an experiment to determine the solubility of BaF2, 500.0 mL of the saturated solution was heated in
an evaporating dish to remove the water. The evaporating dish and the residue were then heated two more
times to ensure all the water was removed.
Volume of the saturated solution of BaF2
Mass of the evaporating dish
Mass of the evaporating dish and BaF2 after the first heating
Mass of the evaporating dish and BaF2 after the second heating
Mass of the evaporating dish and BaF2 after the third heating
500.0 mL
72.540 g
73.500 g
72.855 g
72.855 g
Using the above data, calculate the Ksp for BaF2
6
Answers
6. The equation that represents the equilibrium in a saturated solution of Fe2(SO4)3 is
A. Fe2(SO4)3(s) ⇄ 3Fe2+(aq) + 2SO43-(aq)
B. Fe2(SO4)3(s) ⇄ 2Fe2+(aq) + 3SO43-(aq)
C. Fe2(SO4)3(s) ⇄ 3Fe3+(aq) + 2SO42-(aq)
D. Fe2(SO4)3(s) ⇄ 2Fe3+(aq) + 3SO42-(aq)
7. When equal volumes of 0.20 M K2CrO4 and 0.20 M AgNO3 are mixed, a red precipitate is formed. The
net ionic equation for this reaction is
A.
B.
C.
D.
K+(aq) + NO3-(aq) → KNO3(s)
2Ag+(aq) + CrO42-(aq) → Ag2CrO4(s)
K2CrO4(aq) + 2AgNO3(aq) → Ag2CrO4(s) + 2KNO3(aq)
2Ag+(aq) + CrO4-(aq) + 2K+(aq) + 2NO3-(aq) → Ag2CrO4(s) + 2KNO3(s)
8. Which of the following compounds could be used to prepare a 0.20 M solution of hydroxide ion?
A.
B.
C.
D.
KOH
Fe(OH)3
Mg(OH)2
Zn(OH)2
9. When 250 mL of 0.36 M Sr(OH)2 are added to 750 mL of water, the resulting ion concentrations are
A.
B.
C.
D.
[Sr2+]
[Sr2+]
[Sr2+]
[Sr2+]
= 0.12 M and [OH-] = 0.12 M
= 0.12 M and [OH-] = 0.24 M
= 0.090 M and [OH-] = 0.090 M
= 0.090 M and [OH-] = 0.180 M
10. When equal volumes of 2.0 M Pb(NO3)2 and 2.0 M KCl are mixed,
A.
B.
C.
D.
a precipitate forms because the trial ion product < Ksp
a precipitate forms because the trial ion product > Ksp
a precipitate does not form because the trial ion product < Ksp
a precipitate does not form because the trial ion product > Ksp
11. Consider the following equilibrium: AgCl(s) ⇄ Ag+(aq) + Cl-(aq)
When Br-(aq) is added to a saturated solution of AgCl,
A.
B.
C.
D.
more AgCl dissolves and its solubility product increases.
more AgCl precipitates and its solubility product decreases.
more AgCl dissolves and its solubility product remains constant.
more AgCl precipitates and its solubility product remains constant.
12. The molar solubility of iron II sulphide is
7
A.
B.
C.
D.
3.6
3.0
6.0
7.7
x
x
x
x
10-37 M
10-19 M
10-19 M
10-10 M
13. A solution containing an unknown cation was added to three solutions and the following observations
were recorded:
Solution
NaI
Na2SO4
NaOH
Observation
no precipitate
precipitate
no precipitate
The unknown cation is
A.
B.
C.
D.
Pb2+
Sr2+
Ca2+
Ag+
14. If the solubility of Pb(OH)2 is 0.155 g/L, then the concentration of each ion in a saturated solution is
A.
B.
C.
D.
[Pb2+]
[Pb2+]
[Pb2+]
[Pb2+]
=
=
=
=
0.155 g/L and [OH-] = 0.155 g/L
0.155 g/L and [OH-] = 0.103 g/L
6.43 x 10-4 M and [OH-] = 1.29 x 10-3 M
6.43 x 10-4 M and [OH-] = 6.43 x 10-3 M
15. Which of the following could be used to separate Pb2+ from Ba2+ by precipitation?
A.
B.
C.
D.
Na2S
NaOH
Na2CO3
Na2SO4
16. When dissolved in water, which of the following form a molecular solution?
A.
B.
C.
D.
HCl(g)
NaNO3(s)
CH3OH(l)
K2SO4(s)
17. Which of the following will be most soluble in water at 25 oC.
A.
B.
C.
D.
AgI
PbS
MgSO4
Ba(OH)2
18. At 25 oC, the solubility of Mg(OH)2 is
A.
B.
C.
1. x 10-32 M
1. x 10-12 M
1. x 10-6 M
8
D.
1. x 10-4 M
19. At 25 oC, the solubility of an unknown compound is 7.1 x 10-5 M. The compound is
A.
B.
C.
D.
CuI
AgI
CaCO3
CaSO4
20. When solid AgBr is added to a saturated solution of AgBr, the reaction rates can be described as:
Rate of Dissolving
Rate of Crystalizing
A.
B.
C.
D.
increasing
increasing
decreasing
increasing
increasing
decreasing
increasing
no change
21. The solubility of PbS is 2.9 x 10-14 M. What is the value of the Ksp.
A.
B.
C.
D.
8.4 x 10-28
2.9 x 10-14
5.8 x 10-14
1.7 x 10-7
22. Which of the following causes a precipitate to form when Sr2+(aq) is added but not when Zn2+(aq) is
added?
A.
B.
C.
D.
S2ClSO42CO32-
23. A 3.0 L solution of NiCl2 is found to have a chloride concentration of 0.60 M. The concentration of
nickel II ions is
A.
B.
C.
D.
0.30 M
0.60 M
0.90 M
1.2 M
24. When equal volumes of 0.20 M K2CO3 and 0.2 M Na3PO4 are mixed,
A.
B.
C.
D.
no precipitate will form
a precipitate of K3PO4 will form
a precipitate of Na2CO3 will form
a precipitate of K3PO4 and Na2CO3 will form
25. A solution of AgNO3 is slowly added to a mixture containing 0.10 M I-, Cl-, Br-, and IO3-. The
precipitate which forms first is
9
A.
B.
C.
D.
AgI
AgCl
AgBr
AgIO3
26. Which of the following units can be used to represent solubility?
A.
B.
C.
D.
g
mol
mol/L
mL/s
27. Consider the following equilibrium: CaCO3(s) ⇄ Ca2+(aq) + CO32-(aq)
Which of the following reagents when added to the equilibrium system, would cause more CaCO3 to
dissolve?
A.
B.
C.
D.
KNO3(s)
CaCO3(s)
H2C2O4(s)
Na2CO3(s)
28. Which of the following could be used to precipitate both Mg2+ and Ca2+ from hard water?
A.
B.
C.
D.
lithium sulphate
sodium phosphate
potassium sulphide
ammonium chloride
29. What is the maximum [Ag+] that can exist in 0.20 M NaBrO3?
A.
B.
C.
D.
1.1 x 10-5 M
5.3 x 10-5 M
2.6 x 10-4 M
7.3 x 10-3 M
30. Which of the following ions could be used to separate Cl-(aq) from SO42-(aq) by precipitation?
A.
B.
C.
D.
Ag+
Ca2+
NH4+
Pb2+
31. The Ksp expression for a saturated solution Ca3(PO4)2 is
A.
B.
C.
D.
Ksp
Ksp
Ksp
Ksp
=
=
=
=
[Ca2+][PO43-]
[Ca2+]3[PO43-]2
[3Ca2+][2PO43-]
[3Ca2+][2PO43-]
32. When Ca(OH)2 attains solubility equilibrium, the
10
A.
B.
C.
D.
solution will be saturated
pH will be less than 7
trial Ksp is less than the Ksp
concentrations of the ions are equal
33. Which of the following describes the changes in ion concentrations when 1.0 g of solid ZnS is added
to a saturated solution of ZnS?
A.
B.
C.
D.
[Zn2+]
[S2-]
increases
decreases
increases
remains constant
decreases
decreases
increases
remains constant
34. The net ionic equation for the reaction between Sr(OH)2 and H2SO4 is
A.
H+ + OH- → H2O
B.
Sr2+ + SO42- → SrSO4
C.
Sr(OH)2 + H2SO4 → SrSO4 + 2H2O
D.
Sr2+ + 2OH- + 2H+ + SO42- → SrSO4 + 2H2O
35. The relationship between the solubility and the size of the Ksp is
A.
B.
C.
D.
there is no relationship
the smaller the Ksp the greater the solubility
the greater the Ksp the greater the solubility
the solubility is always the square root of the Ksp
11
36. Which of the following compounds will form a saturated solution with the greatest concentration of
Ag+?
A.
B.
C.
D.
AgI
AgBr
AgIO3
AgBrO3
37. When equal volumes of 0.20 M CuSO4 and 0.20 M Li2S are combined, the complete ionic equation is
A.
B.
C.
D.
Cu2+(aq) + S2-(aq) → CuS(s)
CuSO4(aq) + Li2S(aq) → CuS(s) + Li2SO4(aq)
Cu2+(aq) + SO42-(aq) + 2Li+(aq) + S2-(aq) → CuS(s) + Li2SO4(aq)
Cu2+(aq) + SO42-(aq) + 2Li+(aq) + S2-(aq) → CuS(s) + 2Li+(aq) + SO42-(aq)
38. Which of the following would have the [Fe3+] = 0.020 M?
A.
B.
C.
D.
0.40 L of 0.050 M Fe(NO3)3
0.80 L of 0.020 M Fe2(SO4)3
0.50 L of 0.040 M FeC6H5O7
0.50 L of 0.010 M Fe2(C2O4)3
39. A solution contains both Ag+ and Mg2+ ions. During selective precipitation, these ions are removed
one at a time by adding
A.
B.
C.
D.
I- followed by OHOH- followed by S2SO42- followed by ClNO3- followed by PO43-
40. The solubility of an AB2 type salt is 2.3 x 10-6 M. The salt is
A.
B.
C.
D.
PbBr2
Fe(OH)2
Cu(IO3)2
Mg(OH)2
1. A saturated solution of BaSO4 is given to patients needing digestive tract x-rays.
a) Write an equation that represents the solubility equilibrium
BaSO4(s) ⇄ Ba2+ + SO4212
b) Calculate the [Ba2+] present in the saturated solution.
x2 = 1.1 x 10-10
[Ba2+] = x = 1.0 x 10-5 M
2. Will a precipitate form when 90.0 mL of 1.00 x 10-2 M Cu(NO3)2 and 10.0 mL of
1.00 x 10-2 M NaIO3 are mixed? Explain using appropriate calculations.
Cu(IO3)2(s)
⇄
Cu2+
2IO3-
+
90 x .0100M
100
10 x .0100M
100
0.00900 M
0.00100 M
Trial ion product = (0.00900)(0.00100)2 = 9.0 x 10-9 < 6.9 x 10-8 (Ksp) therefore there is no
precipitate.
3. What is the maximum [CO32-] that can exist in a 1.3 x 10-4 M AgNO3 solution?
Ag2CO3(s)
⇄
2Ag+
+
CO321.3 x 10-4 M
Ksp = [Ag+]2[CO32-]
8.5 x 10-12 = (1.3 x 10-4)2[CO32-]
[CO32-] = 5.0 x 10-4 M
4. The following data was collected when a 25.00 mL sample of water containing chloride ion was titrated
using 0.100M AgNO3 to completely precipitate the chloride ion.
Initial volume of AgNO3
Final volume of AgNO3
18.30 mL
27.22 mL
a) Write the net ionic reaction for the precipitation reaction.
13
Ag+
+
→
Cl-
AgCl(s)
c) Calculate the [Cl-].
[Cl-]
=
0.00892 L Ag+ x 0.100 mole x 1 mole ClL
1 mole Ag+
.0250 L
= 3.57 x 10-2 M
5. In an experiment to determine the solubility of BaF2, 500.0 mL of the saturated solution was heated in
an evaporating dish to remove the water. The evaporating dish and the residue were then heated two more
times to ensure all the water was removed.
Volume of the saturated solution of BaF2
Mass of the evaporating dish
Mass of the evaporating dish and BaF2 after the first heating
Mass of the evaporating dish and BaF2 after the second heating
Mass of the evaporating dish and BaF2 after the third heating
500.0 mL
72.540 g
73.500 g
72.855 g
72.855 g
Using the above data, calculate the Ksp for BaF2
Mass of BaF2 = 72.855 – 72.540 = 0.315g
Molarity
= 0.315g x
1 mole
175.3g
= 0.00359 M
.500L
Ksp = [0.00359][.007188]2
=
1.86 x 10-7
14