PSI AP Chemistry
Equilibrium Multiple Choice
Name_________________________
Part A: Introduction to Equilibrium and ICE Tables
1. At equilibrium, __________.
(A) all chemical reactions have ceased
(B) the rates of the forward and reverse reactions are equal
(C) the rate constants of the forward and reverse reactions are equal
(D) the value of the equilibrium constant is 1
(E) the limiting reagent has been consumed
Use the following information to answer questions 2-3
A(g) ⇌ 2C(g) + D(s)
2. At what time does the reaction below reach equilibrium?
(A) Around 2 minutes
(B) Around 3 minutes
(C) Around 5 minutes
(D) Around 8 minutes
(E) Around 10 minutes
3. What would be the value of the equilibrium constant for the reaction above?
(A) 1.2
(B) 3.6
(C) 0.833
(D) 1.8
(E) 3.0
4. Which of the following compounds is the least soluble?
Compound
MnCO3
CuS
CdS
PbS
Ksp_______
1.8 x 10-11
6.3 x 10-36
8.0 x 10-27
8.0 x 10-28
(A) MnCO3
(B) CuS
(C) CdS
(D) PbS
(E) both CdS and PbS
5. Which of the following expressions is the correct equilibrium-constant expression
for the equilibrium between dinitrogen tetroxide and nitrogen dioxide?
N2O4(g) ⇌ 2NO2(g)
(A) [NO2]/[ N2O4]
(B) [NO2]2/[ N2O4]
(C) [NO2]/[ N2O4]2
(D) [NO2] [ N2O4]
(E) [NO2]2 [ N2O4]
6. Which of the following expressions is the correct equilibrium-constant expression
for the reaction below?
(NH4)2Se(s) ⇌ 2NH3(g) + H2Se(g)
(A) [NH3][ H2Se]/(NH4)2Se
(B) (NH4)2Se/[NH3]2[ H2Se]
(C) 1/[(NH4)2Se ]
(D) [NH3]2[ H2Se]
(E) [NH3]2[ H2Se]/ [(NH4)2Se ]
7. Which of the following expressions is the correct equilibrium-constant expression
for the reaction below?
HF(aq) + H2O(l) ⇌ H3O+(aq) + F-(aq)
(A) [HF][H2O]/ [H3O+][F-]
(B) 1/HF
(C) [H3O+][F-]/[HF][H2O]
(D) [H3O+][F-]/[HF]
(E) [F-]/[HF]
8. The equilibrium-constant expression for the reaction below is____________.
Ti(s) + 2Cl2(g) ⇌ TiCl4(l)
(A) [TiCl4]/[Ti][ Cl2]
(B) [Ti][ Cl2]2/ [TiCl4]
(C) [TiCl4]/[ Cl2]2
(D) [ Cl2]-2
(E) [TiCl4]/[Ti][ Cl2]2
9. The equilibrium constant for the gas phase reaction N2(g) + 3H2(g) ⇌2NH3(g) is Keq
= 4.34x10-3 at 300 °C. At equilibrium, __________.
(A) products predominate
(B) reactants predominate
(C) roughly equal amounts of products and reactants are present
(D) only products are present
(E) only reactants are present
10. The equilibrium constant for the gas phase reaction 2NH3(g) ⇌ N2(g) + 3H2(g) is
Keq = 230 at 300 °C. At equilibrium, __________.
(A) products predominate
(B) reactants predominate
(C) roughly equal amounts of products and reactants are present
(D) only products are present
(E) only reactants are present
11. The reaction A(g) ⇌B(g) has a K value of 4.1 x 102. At equilibrium, which of the
following would be true?
(A) [A] = [B]
(B) [A] > [B]
(C) [A] < [B]
12. The following reactions have equilibrium values all measured at 500 K. Arrange
them in order of increasing tendency to proceed to completion (least completion 
greatest completion).
1) 2NOCl ⇌ 2NO + Cl2
2) N2O4 ⇌ 2NO2
3) 2SO3 ⇌ 2SO2 + O2
4) 2NO2 ⇌ 2NO + O2
(A) 2 < 1 < 3 < 4
(B) 4 < 3 < 1 < 2
(C) 3 < 1 < 4 < 2
(D) 3 < 4 < 1 < 2
(E) 4 < 3 < 2 < 1
Kp = 1.7 x 10-2
Kp = 1.5 x 103
Kp = 1.3 x 10-5
Kp = 5.9 x 10-5
13. Consider the following equilibrium: 2SO2(g) + O2(g) ⇌ 2SO3(g) The equilibrium
cannot be established when __________ is/are placed in a 1.0-L container.
(A) 0.25 mol SO2(g) and 0.25 mol O2(g)
(B) 0.75 mol SO2(g)
(C) 0.25 mol SO2(g) and 0.25 mol SO3(g)
(D) 0.50 mol O2(g) and 0.50 mol SO3(g)
(E) 1.0 mol SO3(g)
14. Consider the following chemical reaction: H2(g) + I2(g) ⇌ 2HI(g). At equilibrium in
a particular experiment, the concentrations of H2, I2, and HI were 0.25M, 0.043M,
and 0.65M respectively. The value of Keq for this reaction is __________.
(A) 60.46
(B) 111
(C) 9.0x10-3
(D) 3.93
(E) 39.30
15. The equilibrium constant (Kp) at 721 K for the reaction 2HI(g) ⇌ H2(g) + I2(g) is
0.0198. In a particular experiment, the partial pressures of H2 and I2 at equilibrium
are 0.710 and 0.888 atm, respectively. The partial pressure of HI is __________ atm.
(A) 7.87
(B) 1.98
(C) 5.64
(D) 0.125
(E) 0.389
16. A reaction vessel is charged with hydrogen iodide, which partially decomposes to
molecular hydrogen and iodine: 2HI(g) ⇌ H2(g) + I2(g). When the system comes to
equilibrium at 425 °C, PHI = 0.808atm, and P(H2) = P(I2) = 0.0860atm. The value of Kp
at this temperature is __________.
(A) 9.15x10-3
(B) 1.30 x10-2
(C) Kp cannot be calculated for this gas reaction when the volume of the reaction
vessel is not given.
(D) 54.3
(E) 1.13 x10-2
17. At high temperatures, molecular hydrogen and molecular bromine react to partially
form hydrogen bromide: H2(g) + Br2(g) ⇌ 2HBr(g) A mixture of 0.682 mol of H2
and 0.440 mol of Br2 is combined in a reaction vessel with a volume of 2.00 L. At
equilibrium at 700 K, there are 0.566 mol of H2 present. At equilibrium, there are
__________ mol of Br2 present in the reaction vessel.
(A) 0.200
(B) 0.480
(C) 0.500
(D) 0.400
(E) 0.324
18. Dinitrogentetraoxide partially decomposes according to the following equilibrium:
N2O4(g) ⇌ 2NO2(g). A 1.00-L flask is charged with 0.055mol of N2O4. At equilibrium
at 373 K, 0.0065 mol of N2O4 remains. Keq for this reaction is __________.
(A) 2.2 x10-4
(B) 0.097
(C) 0.22
(D) 0.0485
(E) 1.45
19. Carbon monoxide is converted to carbon dioxide via the following reaction:
CO(g) + H2O(g) ⇌ CO2(g) + H2(g) In an experiment, 0.45 mol of CO and 0.30 mol of
H2O were placed in a 1.00-L reaction vessel. At equilibrium, there were 0.19 mol of
CO remaining. Keq at the temperature of the experiment is __________.
(A) 4.47
(B) 0.55
(C) 8.89
(D) 0.63
(E) 1.0
20. A sealed 1.0 L flask is charged with 0.600 mol of I2 and 0.600 mol of Br2.
I2(g) + Br2(g) ⇌ 2IBr(g)
When the contents achieve equilibrium, the flask contains 0.80 mol of IBr. The value
of Keq is ______.
(A) 6.4
(B) 4.0
(C) 16
(D) 7.1
(E) 3.5
21. Nitrosyl bromide decomposes according to the following equation.
2NOBr(g) ⇌ 2NO(g) + Br2(g).
A sample of NOBr (0.64 mol) was placed in a 1.00-L flask containing no NO or Br2. At
equilibrium the flask contained 0.46 mol of NOBr. How many moles of NO and Br2,
respectively, are in the flask at equilibrium?
(A) 0.18, 0.18
(B) 0.46, 0.23
(C) 0.18, 0.090
(D) 0.18, 0.360
(E) 0.46, 0.46
22. Two moles of gas A are placed in a one liter vessel and decompose into the gaseous
products B and C according to the equation 2A(g) ⇌ B(g) + C(g). If it is 40.0%
dissociated at equilibrium, what is the value of the equilibrium constant?
(A) .025
(B) .011
(C) .012
(D) .111
23. At 22 °C, Kp = 0.070 for the equilibrium: NH4HS(s) ⇌ NH3(g) + H2S(g)
A sample of solid NH4HS is placed in a closed vessel and allowed to equilibrate.
Calculate the equilibrium partial pressure (atm) of ammonia, assuming that some
solid NH4HS remains.
(A) 0.26
(B) 0.070
(C) 0.52
(D) 4.9 x10-3
(E) 3.8
24. At 100°C the reaction below has an equilibrium constant, Keq, value of 2.2x10-10. If
1.00 mol of phosgene, COCl2, is placed in a 10.0 L flask, calculate the concentration of
carbon monoxide at equilibrium.
COCl2(g) ⇌ CO(g) + Cl2(g)
(A) 0.075
(B) 4.7x10-5
(C) 0.52
(D) 4.7x10-6
(E) 0.154
25. The equilibrium constant (Kp) for the interconversion of PCl5 and PCl3 is 0.0121:
PCl5(g) ⇌ PCl3(g) + Cl2(g) . A vessel is charged with PCl5, giving an initial pressure
of 0.123 atm. At equilibrium, the partial pressure of PCl3 is __________ atm.
(A) 0.0782
(B) 0.0455
(C) 0.0908
(D) 0.0330
(E) 0.123
26. At 200 °C, the equilibrium constant (Kp) for the reaction below is 2.40  103 .
2NO(g) ⇌ N2(g) + O2(g)
A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of
O2 is _________ atm.
(A) 294
(B) 35.7
(C) 17.9
(D) 6.00
(E) 1.50x10-2
27. For which one of the following is the value of Kp smaller than that of Kc at 25øC?
(A) H2(g) + F2(g) ⇌ 2HF(g)
(B) 2SO3(g) ⇌ 2SO2(g) + O2(g)
(C) Al2(SO3)3(s) + 6HCl(g) ⇌ 2AlCl3(s) + 3H2O(l) + 3SO2(g)
(D) NH4Br(s) + KOH(s) ⇌ NH3(g) + KBr(s) + H2O(l)
(E) 2HF(g) ⇌ H2(g) + F2(g)
28. For which one of the following does Kc = Kp at 25øC?
(A) H2(g) + F2(g) ) ⇌ 2HF(g)
(B) 2SO3(g) ⇌ 2SO2(g) + O2(g)
(C) Al2(SO3)3(s) + 6HCl(g) ⇌ 2AlCl3(s) + 3H2O(l) + 3SO2(g)
(D) NH4Br(s) + KOH(s) ⇌ NH3(g) + KBr(s) + H2O(l)
(E) N2(g) + 3 H2(g)  2 NH3(g)
29. Given the following reaction at equilibrium, if Kc = 6.44x105 at 230.0 °C, Kp =
__________.
2NO(g) + O2(g) ⇌ 2NO2(g)
(A) 3.67 x10-2
(B) 1.56 x104
(C) 6.44 x105
(D) 2.66 x106
(E) 2.67 x107
30. Given the following reaction at equilibrium, if Kp =1.05 at 250.0 °C, Kc = __________.
PCl5(g) ⇌ PCl3(g) + Cl2(g)
(A) 3.90x10-6
(B) 2.45x10-2
(C) 1.05
(D) 42.9
(E) 45.0
Part B: Le Chatelier’s Principle, Q, and Calculating K Values
31. At 400 K, the equilibrium constant for the reaction Br2(g) + Cl2(g) ⇌ 2BrCl(g) is
Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br2, 1.00 atm of Cl2, and
2.00 atm of BrCl. Use Q to determine which of the statements below is true.
(A) The equilibrium partial pressures of Br2, Cl2 , and BrCl will be the same as the
initial values.
(B) The equilibrium partial pressure of Br2 will be greater than 1.00 atm.
(C) At equilibrium, the total pressure in the vessel will be less than the initial total
pressure.
(D) The equilibrium partial pressure of BrCl will be greater than 2.00 atm.
(E) The reaction will go to completion since there are equal amounts of Br2 and Cl2.
32. For the reaction, 2SO2(g) + O2(g)
2SO3(g), at 450.0 K the equilibrium constant, Kc, has a value of 4.62. A system was charged to give these initial
concentrations, [SO3] = 0.254 M, [O2] = 0.00855 M, [SO2] = 0.500 M. In which
direction will it go?
(A) to the right or the left depending on the pressure
(B) to the left
(C) it will remain at the same concentrations
(D) to the right
(E) to the right or the left depending on the volume
33. Which of the following statements is true?
(A) Q does not change with temperature.
(B) Keq does not change with temperature, whereas Q is temperature dependent.
(C) K does not depend on the concentrations or partial pressures of reaction
components.
(D) Q does not depend on the concentrations or partial pressures of reaction
components.
(E) Q is the same as Keq when a reaction is at equilibrium.
34. How is the reaction quotient used to determine whether a system is at equilibrium?
(A) The reaction quotient must be satisfied for equilibrium to be achieved.
(B) At equilibrium, the reaction quotient is undefined.
(C) The reaction is at equilibrium when Q < Keq.
(D) The reaction is at equilibrium when Q > Keq.
(E) The reaction is at equilibrium when Q = Keq.
35. Consider the following reaction at equilibrium:
2NH3(g) ⇌ N2(g) + 3H2(g)
ΔH° = +92.4 kJ
Le Chatelier's principle predicts that adding N2 to the system at equilibrium will
result in _________.
(A) a decrease in the concentration of NH3
(B) a decrease in the concentration of H2
(C) an increase in the value of the equilibrium constant
(D) a lower partial pressure of N2
(E) removal of all of the H2
36. Consider the following reaction at equilibrium:
2CO2(g) ⇌ 2CO(g) + O2(g)
ΔH° = -514 kJ
Le Chatelier's principle predicts that adding O2 (g) to the reaction container will____.
(A) increase the partial pressure of CO at equilibrium
(B) decrease the partial pressure of CO2 at equilibrium
(C) increase the value of the equilibrium constant
(D) increase the partial pressure of CO2 at equilibrium
(E) decrease the value of the equilibrium constant
37. Consider the following reaction at equilibrium:
2CO2(g) ⇌ 2CO(g) + O2(g)
ΔH° = -514 kJ
Le Chatelier's principle predicts that an increase in temperature will __________.
(A) increase the partial pressure of O2
(B) decrease the partial pressure of CO2
(C) decrease the value of the equilibrium constant
(D) increase the value of the equilibrium constant
(E) increase the partial pressure of CO
38. Consider the following reaction at equilibrium:
2SO2(g) + O2(g) ⇌ 2SO3(g)
ΔH° = -99 kJ
Le Chatelier's principle predicts that an increase in temperature will result in _______.
(A) a decrease in the partial pressure of SO3
(B) a decrease in the partial pressure of SO2
(C) an increase in Keq
(D) no changes in equilibrium partial pressures
(E) the partial pressure of O2 will decrease
39. Of the following equilibria, only __________ will shift to the left in response to a
decrease in volume.
(A) H2(g) + Cl2(g) ⇌ 2HCl(g)
(B) 2SO3(g) + 2SO2(g) + O2(g)
(C) N2(g) + 3H2(g) ⇌ 2NH3(g)
(D) 4Fe(s) + 3O2(g) ⇌ 2Fe2O3(s)
(E) 2HI(g) ⇌ H2(g) + I2(g)
40. In which of the following reactions would increasing pressure at constant
temperature not change the concentrations of reactants and products, based on Le
Chatelier's principle?
(A) N2(g) + 3H2(g) ⇌ 2NH3(g)
(B) N2O4(g) ⇌ 2NO2(g)
(C) N2(g) + 2O2(g) ⇌ 2NO2(g)
(D) 2N2(g) + O2(g) ⇌ 2N2O(g)
(E) N2(g) + O2(g) ⇌ 2NO(g)
41. The reaction below is exothermic: 2SO2(g) + O2(g) ⇌ 2SO3(g)
Le Chatelier's Principle predicts that __________ will result in an increase in the
number of moles of SO3 in the reaction container.
(A) increasing the pressure
(B) decreasing the pressure
(C) increasing the temperature
(D) removing some oxygen
(E) increasing the volume of the container
42. For the endothermic reaction CaCO3(s) ⇌ CaO(s) + CO2(g), Le Chatelier's principle
predicts that __________ will result in an increase in the number of moles of CO2.
(A) increasing the temperature
(B) decreasing the temperature
(C) increasing the pressure
(D) removing some of the CaCO3
(E) none of the above
43. The effect of a catalyst on equilibrium is to __________.
(A) increase the rate of the forward reaction only
(B) increase the equilibrium constant so that products are favored
(C) slow the reverse reaction only
(D) increase the rate at which equilibrium is achieved without changing the
composition of the equilibrium mixture
(E) shift the equilibrium to the right
44. Consider the following system, which is at equilibrium,
3C(s) + 3H2(g)
CH4(g) + C2H2(g)
The result of removing some C(s) from the system will be:
(A) Kc increases
(B) more C(s) is produced
(C) no further change occurs
(D) more CH4(g) and C2H2(g) are produced to restore the equilibrium
(E) more C2H2(g) is consumed to restore the equilibrium
For questions 45-48, consider the following equilibrium system.
I2(g) +
Cl2(g) ⇄ 2 ICl (g) + heat
(A)
(B)
(C)
(D)
The graphs above represent concentration vs reaction progress. Identify the graph that
best represents each of the following stresses and shift.
45. ________adding I2(g)
46. ________removing Cl2(g)
47. ________increasing the temperature
48. ________increasing the volume
49. Consider the following equilibrium reaction:
N2O4(g)
2NO2(g)
At time t1, heat is applied to the system. Which of the following best describes the
equilibrium reaction and the change in Keq?
(A) exothermic and Keq increases
(B) exothermic and Keq decreases
(C) endothermic and Keq increases
(D) endothermic and Keq decreases
50. Consider the following equilibrium: CH3COOH(aq) ⇄ CH3COO-(aq) + H+(aq) + heat
A stress was applied at time t1 and the data plotted on the following graph:
The stress imposed at time t1 is the result of
(A) the addition of HCl
(B) decreasing the temperature
(C) the addition of NaCH3COO
(D) increasing the volume of the
container
[H+]
time
t1
51. The Keq for the equilibrium below is 0.135 at 700.0 ° C.
SO2(g) + ½O2(g) ⇌ SO3(g).
What is the value of Keq at this temperature for the following reaction?
SO3(g) ⇌ SO2(g) + ½O2(g)
(A) 0.224
(B) 0.0185
(C) 0.112
(D) 7.40
(E) -0.112
52. The value of Keq for the equilibrium H2(g) + I2(g) ⇌ 2HI(g) is 890 at 25 °C. What is
the value of Keq for the equilibrium below?
½H2(g) + ½I2(g) ⇌ HI(g)
(A) 397
(B) 0.035
(C) 29.83
(D) 1588
(E) 0.0013
53. The value of Keq for the following reaction is 0.20:
SO2(g) + NO2(g) ⇌ SO3(g) + NO(g).
The value of Keq at the same temperature for the reaction below is _______.
2SO2(g) + 2NO2(g) ⇌ 2SO3(g) + 2NO(g)
(A) 0.50
(B) 0.04
(C) 0.12
(D) 0.25
(E) 16
54. The value of Keq for the equilibrium H2(g) + I2(g) ⇌ 2HI(g) is 54.0 at 427 °C. What
is the value of Keq for the equilibrium below?
HI(g) ⇌ ½H2(g) + ½I2(g)
(A) 27
(B) 7.35
(C) 0.136
(D) 2.92x103
(E) 3.43x10-4
55. The Keq for the equilibrium below is 6.5x10-2 at 480.0 °C.
2Cl2(g) + 2H2O(g) ⇌ 4HCl(g) + O2(g)
What is the value of Keq at this temperature for the following reaction?
2HCl(g) + ½O2(g) ⇌ Cl2(g) + H2O(g)
(A) 39.2
(B) 3.92
(C) -0.0376
(D) 5.66 x10-3
(E) 0.274
56. Given the two reactions shown with their equilibrium constants,
PCl3(g) + ½ O2(g)
POCl3(g)
K1
NO(g) + ½ O2(g)
NO2(g)
K2
What is the equilibrium constant for the reaction,
PCl3(g) + NO2(g)
POCl3(g) + NO(g)
(A) K1K2
(B) K2/K1
(C) K1/K2
(D) (K1K2)-1
(E) K2-K1
57. The equilibrium constant for the reaction, H2(g) + I2(g)
699.0 K. What is the equilibrium constant for 4 HI(g)
under the same conditions?
2 HI(g) is 54.9 at
2 H2(g) + 2 I2(g)
(A) 109.8
(B) 0.00911
(C) 0.000332
(D) -109.8
(E) 0.0182
58. Using this data,
2 NO(g) + Cl2(g)
2 NOCl(g)
2 NO2(g)
2 NO(g) + O2(g)
Kc = 3.20 x 10-3
Kc = 15.5
calculate a value for Kc for the reaction,
NOCl(g) + ½ O2(g)
NO2(g) + ½ Cl2(g)
(A) 2.06 x 10-4
(B) 4.84 x 10-3
(C) 0.223
(D) 4.49
(E) 20.2
59. The reaction 2A(g) ⇌ B(g) has a K value of 8. What is the value of K for the reaction
½B(g) ⇌ A(g)
(A) 2
(B) 0.125
(C) 0.354
(D) .25
(E) 64
Part C: Solubility Equilibrium
60. Given the reaction at equilibrium: Zn(OH) ↔ Zn2+ + 2OH
What is the expression for the solubility product constant, Ksp, for this reaction?
(A) Ksp = [Zn2+ ][OH-] / [Zn(OH)2]
(B) Ksp = [Zn(OH)2] / [Zn2+ ][2OH-]
(C) Ksp = [Zn2+ ][2OH-]
(D) Ksp = [Zn2+ ][OH-]2
61. Which of the following is the expression for the solubility product of Ca3(PO4)2?
(A) Ksp= [Ca2+]3 [PO43-]2
(B) Ksp= [3 x Ca2+]3 [2 x PO43-]2
(C) Ksp=3[Ca2+] x 2[PO43-]
(D) Ksp=3[Ca2+]3 + 2[PO43-]2
(E) Ksp= [Ca2+]3 [PO43-]2
62. The solubility of lead (II) chloride (PbCl2) is 1.6 x 10-2 M at 25oC. At this
temperature, what is the Ksp of PbCl2?
(A) 5.0 x 10-4
(B) 4.1 x 10-6
(C) 3.1 x 10-7
(D) 1.6 x 10-5
(E) 1.6 x 10-2
63. The solubility of manganese (II) hydroxide (Mn(OH)2) is 2.2 x 10-5 M. What is the Ksp
of Mn(OH)2?
(A) 1.1 x 10-14
(B) 4.3 x10-14
(C) 2.1 x10-14
(D) 4.8 x10-10
(E) 2.2 x 10-5
64. What is the solubility product for AuCl3 if the molar solubility in a saturated solution
is 3.3 x 10-7 M?
(A) 3.3 x 10-27
(B) 1.2 x 10-26
(C) 3.2 x 10-25
(D) 3.3 x 10-13
(E) 1.3 x 10-6
65. The solubility of silver sulfate (Ag2SO4), in moles per liter, can be expressed in terms
of the resulting ion concentrations. Which relationship is correct?
(A) solubility = 2[Ag+]
(B) solubility = [Ag+]
(C) solubility = [2Ag+]
(D) solubility = 2[SO42-]
(E) solubility = [SO42-]
66. Which expression best describes the relationship between solubility product, Ksp,
and the solubility, s, of MgF2?
(A) Ksp = 2x
(B) Ksp = x2
(C) Ksp = 2x3
(D) Ksp = 4x2
(E) Ksp = 4x3
67. What is the solubility, in mol/L, of PbI2, at a temperature where the Ksp = 8.5 x 10-9?
(A) 4.6 x 10-5
(B) 9.2 x 10-5
(C) 1.3 x 10-3
(D) 2.0 x 10-3
68. Calculate the concentration of iodide ion in a saturated solution of lead (II) iodide,
PbI2 (Ksp is 1.4 x 10-8 ).
(A) 4.2 x 10-4
(B) 3.1 x 10-3
(C) 1.5 x 10-3
(D) 3.5 x 10-9
(E) 1.4 x 10-8
69. What is the solubility, in mol/L, of AgBr if the Ksp = 5.0 x 10-13?
(A) 2.5 x 10-25
(B) 1.0 x 10-12
(C) 7.1 x 10-7
(D) 7.1 x 10-6
70. Calculate the solubility in grams per liter (note that Ksp is in terms of moles and
liters) of SrSO4
Ksp = 3.20 x 10−7
(A) 5.67 x 10-4 g/L
(B) 3.2 x 10-7 g/L
(C) 0.104 g/L
(D) 0.208 g/L
(E) None of the above
71. Which of the following compounds is the least soluble?
Compound
MnCO3
CuS
CdS
PbS
Ksp_______
1.8 x 10-11
6.3 x 10-36
8.0 x 10-27
8.0 x 10-28
(A) MnCO3
(B) CuS
(C) CdS
(D) PbS
(E) both CdS and PbS
72. Given the following table of Ksp values, determine which compound listed has the
greatest solubility.
Compound
CdCO3
Cd(OH)2
AgI
Fe(OH)3
ZnCO3
Ksp_______
5.2 x 10- 12
2.5 x 10-14
8.3 x 10-17
4.0 x 10-38
1.4 x 10-11
(A) CdCO3
(B) Cd(OH)2
(C) AgI
(D) Fe(OH)3
(E) ZnCO3
73. Calculate the maximum concentration (in M) of chloride ions (Cl-) in a solution that
contains 0.100 M of Pb2+ if at 323 K the Ksp of PbCl2 is 1.0 x10-4.
(A) 1.0 x10-4
(B) 1.0 x10-3
(C) 0.029
(D) 0.032
(E) 0.058
74. What is the solubility (M) of PbCl2 in a 0.15 M solution of HCl? The Ksp of PbCl2 at
25oC is 1.6 x10-5.
(A) 2.0 x10-3
(B) 1.1 x10-4
(C) 1.8 x10-4
(D) 7.1 x10-4
(E) 1.6 x10-5
75. If 0.1 M aqueous solutions of the following pairs of substances are combined, which
pair will yield a precipitate?
(A) sodium sulfide & ammonium chloride
(B) sodium sulfide & iron (III) chloride
(C) sodium hydroxide & potassium nitrate
(D) nickel (II) nitrate & magnesium chlorate
(E) potassium chloride & aluminum nitrate
76. Will a silver iodate precipitate form when 100 mL of 0.010 M AgNO3 is mixed with
10.0 mL of 0.015 M NaIO3? (Ksp of AgIO3 is 3.1 x 10-8)
(A) No, because Q < K
(B) Yes, because Q < K
(C) No, because Q > K
(D) Yes, because Q > K
(E) Not enough information
77. Will a silver sulfate precipitate form when 100 mL of 0.050 M AgNO3 is mixed with
10.0 mL of 0.0050 M Na2SO4? (Ksp of Ag2SO4 is 1.5 x 10-5)
(A) No, because Q < K
(B) Yes, because Q < K
(C) No, because Q > K
(D) Yes, because Q > K
(E) Not enough information
78. A solution contains 2.0 x 10-4 M Ag+ and 1.5 x 10-3 M Pb2+ . If sodium iodide, NaI is
added, what [I-] will cause the first precipitate? (Ksp= 8.3 x 10-17 for AgI; Ksp= 7.9 x
10-9 for PbI2)
(A) 2.0 x 10-4 M I- will cause AgI to precipitate first
(B) 4.2 x 10-13 M I- will cause AgI to precipitate first
(C) 5.3 x 10-6 M I- will cause PbI2 to precipitate first
(D) 2.3 x 10-3 M I- will cause PbI2 to precipitate first
(E) Not enough information
79. A solution contains 0.010 M Ba2+ and 0.010 M Sr2+. If sodium sulfate, Na2SO4 is
slowly added, what [SO42-] will cause the first precipitate? (Ksp= 1.1 x 10-10 for
BaSO4; Ksp= 3.2 x 10-7 for SrSO4)
(A) 1.1 x 10-8 M SO42- will cause BaSO4 to precipitate first
(B) 1.1 x 10-10 M SO42- will cause BaSO4 to precipitate first
(C) 3.2 x 10-5 M SO42- will cause SrSO4 to precipitate first
(D) 3.2 x 10-7 M SO42- will cause SrSO4 to precipitate first
(E) Not enough information
80. Which of the following compounds will be more soluble if the pH of a saturated
solution is lowered?
(A) AgCl
(B) AgI
(C) PbCl2
(D) NaCl
(E) Cr(OH)3
81. In which of the following aqueous solutions would you expect AgCl to ave the
lowest solubility?
(A) pure water
(B) 0.020 M BaCl2
(C) 0.015 NaCl
(D) 0.020 AgNO3
(E) 0.020 KCl
82. In which of the following aqueous solutions would you expect AgCl to have the
highest solubility?
(A) pure water
(B) 0.020 M BaCl2
(C) 0.015 M NaCl
(D) 0.020 M AgNO3
(E) 0.020 M KCl
Answer Key
1. B
2. B
3. A
4. B
5. B
6. D
7. D
8. D
9. B
10. A
11. B
12. D
13. B
14. E
15. C
16. E
17. E
18. E
19. C
20. C
21. C
22. D
23. A
24. D
25. D
26. C
27. C
28. A
29. B
30. B
31. D
32. B
33. E
34. E
35. B
36. D
37. C
38. A
39. B
40. E
41. A
42. A
43. D
44. C
45. A
46. D
47. B
48. C
49. C
50. C
51. D
52. C
53. B
54. C
55. B
56. C
57. C
58. D
59. C
60. D
61. A
62. D
63. B
64. C
65. E
66. E
67. C
68. B
69. C
70. C
71. B
72. B
73. D
74. D
75. B
76. D
77. A
78. B
79. A
80. E
81. B
82. A
Part A and B Conceptual problems
1. In which of the following systems would the number of moles of the substances
present at equilibrium NOT be shifted by a change in the volume of the system at
constant temperature?
(A) CO(g) + NO(g)  CO2(g) + 1/2 N2(g)
(B) B) N2(g) + 3 H2(g) 2 NH3(g)
(C) N2(g) + 2 O2(g)  2 NO2(g)
(D) N2O4(g)  2 NO2(g)
(E) NO(g) + O3(g)  NO2(g) + O2(g)
2. Which of the following is the correct equilibrium expression for the hydrolysis of
CO32¯ ?
(A) K = [HCO3¯ ] / ( [CO32¯ ] [H3O+] )
(B) K = ( [HCO3¯] [OH¯] ) / [CO32¯]
(C) K = ( [CO32¯ ] [OH¯] ) / [HCO3¯]
(D) K = [CO32¯ ] / ( [CO2] [OH¯]2 )
(E) K = ( [CO32¯ ] [H3O+] ) / [HCO3¯]
3. CuO(s) + H2(g)  Cu(s) + H2O(g); ΔH = - 2.0 kilojoules
When the substances in the equation above are at equilibrium at pressure P and
temperature T, the equilibrium can be shifted to favor the products by
(A) increasing the pressure by means of a moving piston at constant T
(B) increasing the pressure by adding an inert gas such as nitrogen
(C) decreasing the temperature
(D) allowing some gases to escape at constant P and T
(E) adding a catalyst
4. Oxalic acid, H2C2O4, is a diprotic acid with K1 = 5.36 x 10¯2 and K2 = 5.3 x 10¯5. For
reaction below, what is the equilibrium constant?
H2C2O4 + 2 H2O  2 H3O+ + C2O42¯
(A) 5.36 x 10¯2
(B) 5.3 x 10¯5
(C) 2.8 x 10¯6
(D) 1.9 x 10¯10
(E) 1.9 x 10¯13
5. 4 HCl(g) + O2(g)  2 Cl2(g) + 2 H2O(g)
Equal numbers of moles of HCl and O2 in a closed system are allowed to reach
equilibrium as represented by the equation above. Which of the following must be
true at equilibrium?
I. [HCl] must be less than [Cl2].
II. [O2] must be greater than [HCl].
III. [Cl2] must equal [H2O].
(A) I only
(B) II only
(C) I and III only
(D) II and III only
(E) I, II, and III
6. SO3 (g)  2 SO2 (g) + O2 (g)
After the equilibrium represented above is established, some pure O2 (g) is injected
into the reaction vessel at constant temperature. After equilibrium is reestablished,
which of the following has a lower value compared to its value at the original
equilibrium?
(A) Keq for the reaction
(B) The total pressure in the reaction vessel.
(C) The amount of SO3 (g) in the reaction vessel.
(D) The amount of O2 (g) in the reaction vessel.
(E) The amount of SO2 (g) in the reaction vessel.
7. The reaction represented below has an equilibrium constant equal to 3.7 x 104.
Which of the following can be concluded from this information?
HC2H3O2(aq) + CN¯(aq)  HCN(aq)
Acid
base
conj.acid
+ C2H3O2¯(aq)
conj.base
(A) CN¯(aq) is a stronger base than C2H3O2¯(aq)
(B) HCN(aq) is a stronger acid than C2H3O2¯(aq)
(C) The conjugate base of CN¯(aq) is C2H3O2¯(aq)
(D) The equilibrium constant will increase with an increase in temperature.
(E) The pH of a solution containing equimolar amounts of CN¯(aq) and C2H3O2¯(aq))
is 7.0.
8. The energy diagram for the reaction X + Y  Z is shown above. The addition of a
catalyst to this reaction would cause a change in which of the indicated energy
differences?
(A) I only
(B) II only
(C) III only
(D) I and II only
(E) I, II, and III
9. For the equilibrium system: CO(g) + 2 H2(g)  CH3OH(l) , what is Kc ?
(A) Kc= CH3OH/2(CO) (H2)
(B) Kc= CH3OH/(CO) (H2)2
(C) Kc= 1/ 2(CO)(H2)
(D) Kc=1/ (CO)(H2)2
10. Consider the system at equilibrium:
2SO2(g) + O2(g)  2SO3(g) for which ∆H < 0. Which change(s) will increase the
yield of SO3(g)?
I.
Increasing the temperature
II.
Increasing the volume of the container
(A) I only
(B) II only
(C) Both I and II
(D) Neither I nor II
11. H2 (g) + I2(g)  2HI(g) ΔH>0
Which of the following changes to the equilibrium system represented above will
increase the quantity of HI(g) in the equilibrium mixture/
I.
adding H2(g)
II.
increasing the temperature
III.
decreasing the pressure
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II and III
12. HCO3-(aq) + OH-(aq)  H2O(l) + CO32- (aq) ΔH = -41.4kJ
When the reaction above is at equilibrium at 1atm and at 250C, the ratio
[CO32-]/[HCO3-] can be increased by doing which of the following?
(A) Decreasing the temperature
(B) B)Adding acid
(C) C)Adding catalyst
(D) D)Diluting the solution with distilled water
(E) E)Bubbling neon gas through the solution
13. Which statement is correct about a system at equilibrium?
(A) The forward and reverse reactions occur at identical rates.
(B) The concentrations of reactants must equal the concentrations of the products.
(C) The concentrations of reactants and products can be changed by adding a
catalyst.
(D) The concentrations of reactants and products are not affected by a change in
temperature
14. For which reaction at equilibrium will an decrease in volume at constant
temperature cause a decrease in the amount of product?
(A) (A) N2 (g) + 3H2 (g)  2NH3(g)
(B) (B) HCl(g) + H2O(l)  H3O+(aq) + Cl–(aq)
(C) Fe3O4 (s) + 4H2(g)  3Fe(s) + 4H2O(g)
(D) CaCO3(s)  CaO(s) + CO2(g)
15. P4(s) + 5 O2(g)  P4O10(s) The equilibrium constant is
(A) Kc = [P4O10] / [P4] [O2]5
(B) Kc = [P4O10] / 5 [P4] [O2]
(C) Kc = [O2]5
(D) Kc = 1 / [O2]5
16. Fe3O4(s) + 4 H2(g)  3 Fe(s) + 4 H2O(g)
ΔH > 0
For this reaction at equilibrium, which changes will increase the quantity of Fe(s)?
1. increasing temperature
2. decreasing temperature
3. adding Fe3O4(s)
(A) 1 only
(B) 1 and 2 only
(C) 2 and 3 only
(D) 1,2, and 3
17. What is the relationship between the equilibrium constant (Kc) of a reaction and the
rate constants for the forward (kf) and backward (kb) steps?
(A) Kc = kf kb
(B) Kc = kb / kf
(C) Kc = kf / kb
(D) Kc = 1 / (kfkb)
18. Which factors will affect both the position of equilibrium and the value of the
equilibrium constant for this reaction? The H = - 92 kJ, N2(g) + 3 H2(g)  2
NH3(g)
(A) increasing the volume of the container
(B) adding N2
(C) removing NH3
(D) lowering the temperature
19. For which reaction at equilibrium does a decrease in volume of the container cause
a decrease in product(s) at constant temperature?
(A) CaCO3 (s)  CaO(s) + CO2(g)
(B) B) 2SO2 (g) + O2 (g)  2SO3(g)
(C) C) HCl(g) + H2O(l)  H3O+(aq) + Cl–(aq)
(D) D) SO2(g) + NO2(g)  SO3(g) + NO(g)
20. N2O4(g)  2NO2(g)
The equilibrium reaction shown is endothermic as written. Which change will
increase he mount of NO2 at equilibrium?
(A) adding a catalyst
(B) decreasing the temperature
(C) increasing the volume of the container
(D) adding an inert gas to increase the pressure
21. 2SO2(g) + O2(g)  2SO3(g) ∆H < 0
Which change(s) will increase the quantity of SO3 (g) at equilibrium?
I.
increasing the temperature
II.
reducing the volume of the container
III.
adding He to increase the pressure
(A) I only
(B) II only
(C) I and III only
(D) II and III only
Part C Conceptual Problems
22. The best explanation for the solubility of MnS in dil HCl is that
(A) The solubility product of MnCl2 is less than that of MnS
(B) Concentration of Mn2+ is lowered by the formation of comples ions with chloride
ions
(C) Concentration of sulphide ions is lowered by oxidation of free sulphur
(D) Concentration of sulphide ions is lowered by the formation of the weak H2S
(E) Because of the formation of more MnCl2
23. The solubility of AgI in NaI solution is less than that in pure water because
(A) AgI forms comples with NaI
(B) of common ion effect
(C) solubility product of AgI is less than that of NaI
(D) the temperature of the solution decreases
(E) none of the above
24. the solubility product of CuS, Ag2S and HgS are 10-31, 10-44 and 10-54 respectively.
The solubility of these sulphides are in the order
(A) Ag2S> CuS >HgS
(B) Ag2S > HgS > CuS
(C) HgS> Ag2S > CuS
(D) CuS > Ag2S > HgS
(E) HgS > CuS > Ag2S
25. What is the correct expression for the solubility product of SnS2 ?
(A) [Sn2+] [S2-]2
(B) [Sn4+] [S2-]2
(C) [Sn2+] [2S2-]2
(D) [Sn4+] [2S2-]2
(E) [Sn2+]2 [S2-]2
26. The solubility of CaCO3 in water is 3.05 x10-4 moles/L. Its solubility product will be
(A) 6.1 x10-4
(B) 9.3
(C) 3.05 x10-4
(D) 9.3 x 10-8
(E) 15.4
27. The solubility of A2X3 is y mol dm-3. Its solubility product is
(A) 6y4
(B) 64y4
(C) 36y5
(D) 108y5
(E) 6y5
28. Consider the following solubility data for various chromates at 25oC.
Ksp
Ag2CrO4
9.0 x 10-12
BaCrO4
2.0 x 10-10
PbCrO4
1.8 x 10-14
The chromate that is the most soluble in water at 25oC on a molar basis is:
(A) Ag2CrO4
(B) BaCrO4
(C) C) PbCrO4
(D) D) impossible to determine
(E) E) none of these
29. What is the molar solubility, s, of Ba3(PO4)2 in terms of Ksp?
(A) s = Ksp1/2
(B) B)) s = Ksp1/5
(C) s = [Ksp/27]1/5
(D) s = [Ksp/108]1/5
(E) s = [Ksp/4]5
30. Ag3PO4 would be least soluble at 25oC in
(A) 0.1 M AgNO3
(B) 0.1 M HNO3
(C) pure water
(D) 0.1 M Na3PO4
(E) solubility in (a), (b), (c), or (d) is not different
31. When we mix together, from separate sources, the ions of a slightly soluble ionic
salt, the salt will precipitate if Qsp _____ Ksp, and will continue to precipitate until
Qsp _____ Ksp.
(A) is greater than; equals
(B) is less than; is greater than
(C) is less than; equals
(D) equals; is less than
(E) equals; is greater than
32. Which of the following pairs of compounds gives a precipitate when aqueous
solutions of them are mixed? Assume that the concentrations of all compounds are
1.0 M immediately after mixing.
(A) CuBr2 and K2CO3
(B) HNO3 and NH4I
(C) BaCl2 and KClO4
(D) Na2CO3 and H2SO4
(E) KCl and KNO3
33. Which of the following occurs when excess of concentrated NH3 (aq) is mixed with
0.1M Cu(NO3)2(aq) ?
(A) A dark red precipitate forms and settles out
(B) Separate layers of immiscible liquids form with a blue layer on top.
(C) The color of the solution turns from light blue to dark blue.
(D) Bubbles of ammonia gas form.
(E) The pH of the solution decreases.
34. A yellow precipitate forms when 0.2 M NaI is added to a 0.2M solution of which of
the following ions?
(A) Zn2+
(B) Pb2+
(C) CrO4 2(D) SO42(E) OH35. Which solution below could selectively precipitate lead alone from the mixture if it
has Fe2+, Cu2+ and Pb2+ ions?
(A) sodium sulfide
(B) soium hydroxide
(C) dil. Hydrochloric acid
(D) dil Nitric acid
(E) dil Ammonia
36. When 50 ml each of 0.1 M Li3(PO4) and Ag(NO3) are mixed together, yellow
precipitate of silver phosphate is produced. Which of the following ions is the major
component in the solution?
(A) [PO43- ]
(B) [NO3-]
(C) [Ag+]
(D) [Li3+]
(E) They are all equal
37. If 100ml each of 0.1M of Ba(OH)2 and Na2 (SO4) are mixed together, what would be
the concentration of the hydroxide ions in solution?
(A) 0.2 M
(B) 0.1M
(C) 1.0M
(D) .02M
(E) 0.01M
38. Referring to the above question, what would be the concentration of [SO42-] ions in
the resulting solution?
(A) 0.1M
(B) 0.5M
(C) 1.0M
(D) negligible amount
(E) 0.05M
39. When aqueous NH3 is first added to a solution containing Ni2+, a precipitate forms,
but when an excess of aqueous NH3 is added, the precipitate dissolves. Which of the
below explains why the precipitate dissolves?
(A) Ni2+ forms hydrogen bonds with NH3
(B) Ni2+ forms hydrogen bonds with NH3
(C) Ni2+ forms complex ion with NH3
(D) Ni2+ is oxidized to Ni3+
(E) Ni2+ is reduced to Ni1+
40. Which of the following ions are generally insoluble in cold water?
(A) Acetate
(B) Potassium
(C) Phosphate
(D) Nitrate
(E) Ammonium
41. A student mixes equal volumes of 1.0M solutions of Tin chloride and 1.0 M copper
sulfate and observes that no precipitate forms. Then the student mixes equal
volumes of 1.0 M solutions of sodium sufide and copper sulfide and observes the
formation of a precipitate. The formula of the precipitate must be
(A) CuS
(B) CuCl2
(C) CuCl
(D) Na2(SO4)2
(E) NaSO4
Conceptual Problems Answer Key
1. E
2. B
3. B
4. C
5. C
6. B
7. A
8. D
9. D
10. A
11. C
12. A
13. A
14. A
15. D
16. A
17. C
18. D
19. A
20. C
21. B
22. D
23. B
24. A
25. B
26. D
27. A
28. A
29. D
30. A
31. A
32. A
33. C
34. B
35. C
36. D
37. C
38. D
39. C
40. C
41. A