CJ Bianconi
CHEM 102 Mock Exam 3
Fall 2015
Soluble Ionic Compounds
*Student-memorized items
Exceptions
All chlorate (ClO3-) and perchlorate (ClO4-) salts
All chloride (Cl-), bromide (Br-), and iodide (I-) salts
Compounds also containing lead, silver, or
mercury(I) (Pb2+, Ag+, Hg22+) are insoluble.
All fluoride (F-) salts
Compounds also containing calcium, strontium,
barium, or lead (Ca2+, Sr2+, Ba2+, Pb2+) are insoluble.
All sulfate (SO42-) salts
Insoluble Ionic Compounds
Compounds also containing calcium, silver,
mercury(I), strontium, barium, or lead (Ca2+, Ag+,
Hg22+, Sr2+, Ba2+, Pb2+) are insoluble.
Exceptions
Hydroxide (OH-) and oxide (O2-) compounds
Compounds also containing barium (Ba2+) and the
student-memorized items are soluble.
Sulfide (S2-) salts
Compounds also containing barium (Ba2+) and the
student-memorized items are soluble.
Carbonate (CO32-) and phosphate (PO43-) salts
Compounds also containing the student-memorized
items are soluble.
Constants:
R = 0.08206 L•atm/mol•K = 8.314 J/mol•K
1 atm = 760 mmHg
(Assume all solutions have water as the solvent unless otherwise indicated. Assume all temperatures are
25°C unless otherwise indicated.)
1. A strong electrolyte exists predominantly as
___ in solution.
5. H3PO4 is a ___.
A. strong acid
A. atoms
B. molecular base
B. ions
C. weak acid
C. molecules
D. soluble ionic compound
D. electrons
E. strong base
E. an isotope
2. Which of the following is temperaturedependent?
6. Which of the following expressions is the
correct equilibrium-constant expression for
the given system?
2 BrCl (g) ⇄ Br2 (g) + Cl2 (g)
A. molality
B. Keq
C. ΔH
D. all of the above
3. Select the one best statement: Freezing point
depression ___.
A. occurs only for molecular solutes
A. 𝐾𝐶 =
B. 𝐾𝐶 =
C. 𝐾𝐶 =
D. 𝐾𝐶 =
[𝐵𝑟2 ][𝐶𝑙2 ]
2[𝐵𝑟𝐶𝑙]
[𝐵𝑟𝐶𝑙]2
[𝐵𝑟2 ][𝐶𝑙2 ]
[𝐵𝑟2 ][𝐶𝑙2 ]
[𝐵𝑟𝐶𝑙]2
2[𝐵𝑟𝐶𝑙]
[𝐵𝑟2 ][𝐶𝑙2 ]
B. occurs only for ionic solutes
For the next three true/false questions,
C. will also occur if the vapor pressure
consider the following graph of the system
of the solution is reduced
A ⇄ B.
D. is the change in freezing point
observed when one goes to a higher
elevation
E. occurs only at S.T.P. (standard
temperature and pressure)
4. A solution of CH3OH in water is found at
Xmethanol = 0.280. What is the vapor pressure
of water in the solution, if the vapor pressure
of pure water is 23.8 mmHg?
A. 17.1 mmHg
7. At equilibrium, more reactants exist than
products.
8. After half of the depicted time has occurred,
B. 6.66 mmHg
the forward and reverse reactions stop
C. 85.0 mmHg
occurring.
D. 33.1 mmHg
9. The K will be substantially greater than 1.
10. The KC for the equilibrium below is
1.0 • 10-14 at 25°C.
2 H2O (l) ⇄ H3O+(aq) + OH-(aq)
What is the value of KC at this temperature
for the following reaction?
½ H3O+(aq) + ½ OH-(aq) ⇄ H2O (l)
A. 1.0 • 1014
14. The vapor pressure of pure ethanol
(CH3CH2OH) at 60°C is 0.495 atm. A
solution prepared by dissolving 128.17 g
naphthalene (C10H8) in 460.7 g of ethanol
will have a vapor pressure of ___.
A. 0.45 torr
B. 34.2 torr
C. 105 torr
B. 1.0 • 10-7
D. 342 torr
C. 1.0 • 10
7
15. If the reaction question Q for a reaction is
D. -14.0 • 10
1
11. Hydronium is ___.
A. the conjugate acid of hydroxide
B. the conjugate base of hydroxide
C. the conjugate acid of water
D. the conjugate base of water
12. The Law of Mass Action states that ___.
A. matter cannot be created or
destroyed in a chemical reaction
B. an equilibrium constant can be
calculated by taking the equilibrium
concentrations of a system
C. an equilibrium system will try to
greater than the value of the equilibrium
constant K for that reaction at a given
temperature, ___ must be converted to ___
for the system to reach equilibrium.
A. reactants, products
B. products, reactants
C. heat, energy
16. If the equilibrium constant for 2A + 2B ⇄ C
is 0.0572 at 25°C, then the equilibrium
constant for 3 C ⇄ 6 A + 6 B is ___.
A. 1.87 • 10-4
B. 5340
offset any disturbances introduced to
C. 2.60
it
D. 0.385
D. when Q < K, the forward reaction
will occur
13. A substance that can act as an acid or a base
is referred to as ___.
A. acibasic
B. amphoteric
C. amphoscopic
D. ampharos
For the next three questions, consider the following
Identify whether the K value indicates a complete
equilibrium system:
reaction, no reaction, a product-favored equilibrium,
CH4 (g) + 2 O2 (g) ⇄ CO2 (g) + 2 H2O (g) ΔH = -890 kJ
a reactant-favored equilibrium, or an equilibrium
with substantial amounts of everything present.
17. Adding CH4 to the system will ___.
A. cause an increase in [O2]
B. have no effect
C. cause [CO2] to increase
D. decrease the [H2O]
18. Lowering the temperature of the system will
22. KC = 233.45
23. KC = 11,100,000
24. KC = 50
25. KC = 0.000000535
26. KC = 2.3E-4
27. KC = 1.11E+7
___.
A. decrease the [H2O]
B. increase the [CH4]
C. decrease the [CH4]
D. cannot be determined
19. Increasing the volume of the beaker in
which the system is contained in will ___.
A. increase the [H2O]
B. have no effect
C. decrease the [CO2]
28. KC = 8.9 • 1044
29. KC = 0.7
30. KC = 8.22E-32
31. KC = 1/24,330,000
32. KC = 6.52 • 103
33. KC = 0.333333333
34. KC = 2.5E+5
35. KC = 1.4 • 10-2
36. KC = 1
D. cause the temperature to drop
37. What is the vapor pressure at 20 °C of a
20. The conjugate base of HPO42- is ___.
A. H3PO4
solution prepared by the addition of 5.33 g
of the nonvolatile solute urea, CO(NH2)2, to
B. H2PO4-
41.1 g of methanol, CH3OH? The vapor
C. PO43-
pressure of pure methanol at 20 °C is 89.0
D. HPO42- has no conjugate base
mmHg.
21. According to Bronsted-Lowry, acids are
A. 0.935 mmHg
B. 83.2 mmHg
___.
A. illegal hallucinogens
B. substances that donate protons
C. substances that produce H3O+ when
added to water
C. 5.76 mmHg
D. 69.1 mmHg
38. Consider the following equilibrium:
For the next two questions, consider the following
S (s) + O2 (g) ⇌ SO2 (g)
reaction initially at equilibrium:
The proper equilibrium expression is KC =
CH4 (g) + CCl4 (g) ⇌ 2 CH2Cl2 (g) ΔH = +10 kJ
_____.
A.
41. Which of the following changes will cause
[SO 2 ]
[S][O 2 ]
2
B.
C.
D.
the formation of CH4 gas?
A. Removal of some CCl4 gas.
[SO]
[O]2
B. Increasing the volume of the
[SO 2 ]
[O 2 ]
C. Increasing the temperature.
[S][O 2 ]
[SO 2 ]
E. None of the above.
39. A sample of HI gas was allowed to come to
container.
D. All of the above.
42. Which of the following best describes the
forward reaction?
come to equilibrium at 448 °C.
A. Endothermic
2 HI (g) ⇌ H2 (g) + I2 (g)
B. Exothermic
At equilibrium, [HI] = 0.0850 M, [H2] =
0.0120 M, and [I2] = 0.0120 M. What is the
KC for this equilibrium?
43. The equilibrium constant, K, for the
A. 1.69 x 10-3
following reaction is 2.3 x 10-4 at 300 °C:
B. 590.
N2 (g) + C2H2 (g) ⇌ 2 HCN (g)
C. 1.99 x 10-2
Calculate the equilibrium concentration of
D. 50.2
HCN when 0.555 moles of N2 and 0.555
40. Which of the following statements is true
regarding the following reaction if it is in
moles of C2H2 are introduced into a 0.500 L
vessel at 300 °C.
equilibrium?
A. 0.00835 M
A⇌B
B. 0.0167 M
A. The amount of A decreases with
time.
B. The amount of B does not change
with time.
C. The rate of the reverse reaction is
zero.
D. The temperature is increasing with
time.
C. 0.00418 M
D. 2.79 x 10-4 M
44. The conjugate base of HCO3- is ___.
A. H2CO3
B. H2CO3+
C. HCO3D. CO3
E. CO3
2-
45. A solution that turns litmus paper blue and is
nonreactive with metals is a/an ___.
A. Acid
B. Base
C. Compound
D. Diatomic element
46. What role is water performing in the
following reaction?
NaHS (aq) + H2O (l) ⇌ H2S (aq) + OH- (aq)
+ Na+ (aq)
A. It is an Arrhenius acid.
B. It is an Arrhenius base.
C. It is a Bronsted-Lowry acid.
D. It is a Bronsted-Lowry base.
47. If the KC for a reaction is 222.5, what must
the reaction quotient be in order for the
forward reaction to occur?
A. Reaction quotient IS KC, so the
system is at equilibrium.
B. The reaction quotient must be less
than KC.
C. The reaction quotient must be greater
than KC.
D. Both the forward and the reverse
reactions must occur at the same
rate.
Identify the acid/base nature of the following
compounds.
48. CH3NH3Br
49. Ag2+
50. CH3COOH
51. HNO2
52. SO2
53. CuCl3
54. Ba(OH)2
55. NO356. KF
57. Ca2+
58. HI
59. C6H5NH2
60. AlBr3
61. HNO3
62. SO3263. Mg(OH)2
64. H2S
65. LiI
66. K2SO4
67. Co2+
68. BeCl2
69. NH4NO3
70. ZnClO4
71. Sr2+
72. H2O
73. Fe3+
74. The TF of 6.23g (NH4)2S dissolved in 13.77g of H2O is -2.56°C. What is the KF of this solution?
75. Calculate П for a solution of 290.25 g Ca(NO3)2 in 1 L of water at 25°C.
76. What is the boiling point of a solution that weighs 12.5 g and contains 0.025 mol NaBr. The Kb of water
is 0.512 °C/m.
77. Find the freezing point of a solution that contains 3.00 g of K2SO4 and 8.5 g of benzene (C6H12). Pure
benzene freezes at 5.5°C and the Kf of benzene is 5.12 °C/m.