Chemistry: The Central Science, 12e (Brown et al.)
Chapter 15 Chemical Equilibrium
15.1 Multiple–Choice Questions
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
2) What role did Karl Bosch play in development of the Haber-Bosch process?
A) He discovered the reaction conditions necessary for formation of ammonia.
B) He originally isolated ammonia from camel dung and found a method for purifying it.
C) Haber was working in his lab with his instructor at the time he worked out the process.
D) He developed the equipment necessary for industrial production of ammonia.
E) He was the German industrialist who financed the research done by Haber.
3) In what year was Fritz Haber awarded the Nobel Prize in chemistry for his development of a process
for synthesizing ammonia directly from nitrogen and hydrogen?
A) 1954
B) 1933
C) 1918
D) 1900
E) 1912
4) Which one of the following is true concerning the Haber process?
A) It is a process used for shifting equilibrium positions to the right for more economical chemical
synthesis of a variety of substances.
B) It is a process used for the synthesis of ammonia.
C) It is another way of stating Le Châtelier’s principle.
D) It is an industrial synthesis of sodium chloride that was discovered by Karl Haber.
E) It is a process for the synthesis of elemental chlorine.
5) Which one of the following will change the value of an equilibrium constant?
A) changing temperature
B) adding other substances that do not react with any of the species involved in the equilibrium
C) varying the initial concentrations of reactants
D) varying the initial concentrations of products
E) changing the volume of the reaction vessel
6) 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)
2
24
NO
NO
B)
2
2
24
NO
NO
C)
2
2
24
NO
NO
D) [NO2][N2O4]
E) [NO2]2[N2O4]
7) Which of the following expressions is the correct equilibrium-constant expression for the following
reaction?
CO2 (g) + 2H2 (g) CH3OH (g)
A)
3
2
CH OH
CO
B)
3
22
CH OH
CO H
C)
2
22
3
CO H
CH OH
D)
22
3
CO H
CH OH
E)
3
2
22
CH OH
CO H
8) The equilibrium-constant expression depends on the __________ of the reaction.
A) stoichiometry
B) mechanism
C) stoichiometry and mechanism
D) the quantities of reactants and products initially present
E) temperature
9) The equilibrium constant for reaction 1 is K. The equilibrium constant for reaction 2 is __________.
(1) SO2 (g) + (1/2) O2 (g) SO3 (g)
(2) 2SO3 (g) 2SO2 (g) + O2 (g)
A) K2
B) 2K
C) 1/2K
D) 1/K2
E) -K2
10) The value of Keq for the following reaction is 0.25:
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) 0.063
C) 0.12
D) 0.25
E) 16
11) The equilibrium expression for Kp for the reaction below is __________.
2O3 (g) 3O2 (g)
A)
2
3
3PO
2PO
B)
3
2
2PO
3PO
C)
3
2
3PO
2PO
D)
2
3
2
2
PO
PO
E)
3
2
2
3
PO
PO
12) The equilibrium expression for Kp for the reaction below is __________.
N2 (g) + O2 (g) 2NO (g)
A)
( )( )
22
22
2 NO
PO PN
P
B)
( )( )
22
2 NO
PO PN
P
C)
( )( )
22
NO
PO PN
P
D)
( )
( )( )
22
2 NO
2 N 2
P
P PO
E) none of the above
13) The Keq for the equilibrium below is 7.52 × 10-2 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?
4HCl (g) + O2 (g) 2Cl2 (g) + 2H2O (g)
A) 0.0752
B) -0.0752
C) 13.3
D) 5.66 × 10-3
E) 0.150
14) The Keq for the equilibrium below is 5.4 × 1013 at 480.0°C.
2NO (g) + O2 (g) 2NO2 (g)
What is the value of Keq at this temperature for the following reaction?
4NO (g) + 2O2 (g) 4NO2 (g)
A) 5.4 × 1013
B) 5.4 × 10-13
C) 1.9 × 1012
D) 1.9 × 10-12
E) 2.9 × 1027
15) The Keq for the equilibrium below is 7.52 × 10-2 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) +
1
2
O2 (g) Cl2 (g) + H2O (g)
A) 13.3
B) 3.65
C) -0.0376
D) 5.66 × 10-3
E) 0.274
16) The Keq for the equilibrium below is 5.4 × 1013 at 480.0°C.
2NO (g) + O2 (g) 2NO2 (g)
What is the value of Keq at this temperature for the following reaction?
NO2 (g) NO (g) + 1/2 O2 (g)
A) 5.4 × 10-13
B) 5.4 × 1013
C) 1.4 × 10-7
D) 5.66 × 10-3
E) none of the above
17) The Keq for the equilibrium below is 0.112 at 700.0°C.
SO2 (g) +
1
2
O2 (g) SO3 (g)
What is the value of Keq at this temperature for the following reaction?
2SO2 (g) + O2 (g) 2SO3 (g)
A) 0.224
B) 0.335
C) 0.0125
D) 0.0560
E) 0.112
18) The Keq for the equilibrium below is 0.112 at 700.0°C.
SO2 (g) +
1
2
O2 (g) SO3 (g)
What is the value of Keq at this temperature for the following reaction?
SO3 (g) SO2 (g) +
1
2
O2 (g)
A) 0.224
B) 0.0125
C) 0.112
D) 8.93
E) -0.112
19) The Keq for the equilibrium below is 0.112 at 700.0°C.
SO2 (g) +
1
2
O2 (g) SO3 (g)
What is the value of Keq at this temperature for the following reaction?
2SO3 (g) 2SO2 (g) + O2 (g)
A) 79.7
B) 2.99
C) 17.86
D) 4.46
E) 8.93
20) Given the following reaction at equilibrium, if Kc = 1.90 × 1019 at 25.0°C, Kp = __________.
H2 (g) + Br2 (g) 2 HBr (g)
A) 5.26 × 10-20
B) 1.56 × 104
C) 6.44 × 105
D) 1.90 × 1019
E) none of the above
21) Which of the following expressions is the correct equilibrium-constant expression for the reaction
below?
2SO2 (g) + O2 (g) 2SO3 (g)
A) [SO3] / [SO2][O2]
B) [SO2] / [SO3]
C) [SO3]2 / [SO2]2[O2]
D) [SO3]2 / [SO2]2[O2]2
E) [SO3] / [SO2][O2]2
22) 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]
23) Which of the following expressions is the correct equilibrium-constant expression for the reaction
below?
CO2 (s) + H2O (l) H+ (aq) + HCO3– (aq)
A) [H+][HCO3–] / [CO2]
B) [CO2] / [H+][HCO3–]
C) [H+][HCO3–] / [CO2][H2O]
D) [CO2][H2O] / [H+][HCO3–]
E) [H+][HCO3–]
24) 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]
25) The expression for Kp for the reaction below is __________.
4CuO (s) + CH4 (g) CO2 (g) + 4Cu (s) + 2H2O (g)
A)
4
2
22
PCH
PCO PH
B)
2
22
4
4
Cu PCO PH O
CuO PCH
C)
2
22
4
PCO PH O
PCH
D)
2
22
PCO PH O
PCuO
E)
4
2
22
PCH
PH O PCO
26) The equilibrium-constant expression for the reaction
Ti (s) + 2Cl2 (g) TiCl4 (l)
is given by
A)
( )
( ) ( )
4
2
TiCl l
Ti s Cl g
B)
( ) ( )
( )
2
2
Ti s Cl g
TiCl4 l
C)
( )
( )
4
2
2
TiCl l
Cl g
D) [Cl2 (g)]-2
E)
( )
( ) ( )
4
2
2
TiCl l
Ti s Cl g
27) The equilibrium constant for the gas phase reaction
N2 (g) + 3H2 (g) 2NH3 (g)
is Keq = 4.34 × 10-3 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
28) The equilibrium constant for the gas phase reaction
2SO2 (g) + O2 (g) 2SO3 (g)
is Keq = 2.80 × 102 at 999 K. 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
29) 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
30) The equilibrium constant for the gas phase reaction
N2 (g) + O2 (g) 2NO (g)
is Keq = 4.20 × 10-31 at 30°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
31) 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 of SO2 (g) and 0.25 mol of SO3 (g)
D) 0.50 mol O2 (g) and 0.50 mol SO3 (g)
E) 1.0 mol SO3 (g)
32) 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 (g), 1.00 atm of Cl2 (g), and 2.00
atm of BrCl (g). 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 (g) will be greater than 2.00 atm.
E) The reaction will go to completion since there are equal amounts of Br2 and Cl2.
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) Of the following equilibria, only __________ will shift to the left in response to a decrease in
volume.
A) H2 (g) + Cl2 (g) 2 HCl (g)
B) 2 SO3 (g) 2 SO2 (g) + O2 (g)
C) N2 (g) + 3 H2 (g) 2 NH3 (g)
D) 4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s)
E) 2HI (g) H2 (g) + I2 (g)
36) Of the following equilibria, only __________ will shift to the right in response to a decrease in
volume.
A) H2 (g) + Cl2 (g) 2 HCl (g)
B) 2 SO3 (g) 2 SO2 (g) + O2 (g)
C) N2 (g) + 3 H2 (g) 2 NH3 (g)
D) 2 Fe2O3 (s) 4 Fe (s) + 3 O2 (g)
E) 2HI (g) H2 (g) + I2 (g)
37) The reaction below is exothermic:
2SO2 (g) + O2 (g) 2SO3 (g)
Le Châtelier’s Principle predicts that __________ will result in an increase in the number of moles of
SO3 (g) 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
38) For the endothermic reaction
CaCO3 (s) CaO (s) + CO2 (g)
Le Châtelier’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 (s)
E) none of the above
39) In which of the following reactions would increasing pressure at constant temperature not change
the concentrations of reactants and products, based on Le Châtelier’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)
40) In which of the following reactions would increasing pressure at constant temperature change the
concentrations of reactants and products, based on Le Châteliers 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) all of the above
41) Consider the following reaction at equilibrium:
2NH3 (g) N2 (g) + 3H2 (g) ΔH° = +92.4 kJ
Le Châtelier’s principle predicts that adding N2 (g) to the system at equilibrium will result in
__________.
A) a decrease in the concentration of NH3 (g)
B) a decrease in the concentration of H2 (g)
C) an increase in the value of the equilibrium constant
D) a lower partial pressure of N2
E) removal of all of the H2 (g)
42) Consider the following reaction at equilibrium:
2NH3 (g) N2 (g) + 3H2 (g)
Le Châtelier’s principle predicts that the moles of H2 in the reaction container will increase with
__________.
A) some removal of NH3 from the reaction vessel (V and T constant)
B) a decrease in the total pressure (T constant)
C) addition of some N2 to the reaction vessel (V and T constant)
D) a decrease in the total volume of the reaction vessel (T constant)
E) an increase in total pressure by the addition of helium gas (V and T constant)
43) Consider the following reaction at equilibrium:
2CO2 (g) 2CO (g) + O2 (g) ΔH° = -514 kJ
Le Châtelier’s principle predicts that adding O2 (g) to the reaction container will __________.
A) increase the partial pressure of CO (g) at equilibrium
B) decrease the partial pressure of CO2 (g) at equilibrium
C) increase the value of the equilibrium constant
D) increase the partial pressure of CO2 (g) at equilibrium
E) decrease the value of the equilibrium constant
44) Consider the following reaction at equilibrium:
2CO2 (g) 2CO (g) + O2 (g) ΔH° = -514 kJ
Le Châtelier’s principle predicts that an increase in temperature will __________.
A) increase the partial pressure of O2 (g)
B) decrease the partial pressure of CO2 (g)
C) decrease the value of the equilibrium constant
D) increase the value of the equilibrium constant
E) increase the partial pressure of CO
45) Consider the following reaction at equilibrium:
C (s) + H2O (g) CO (g) + H2 (g)
Which of the following conditions will increase the partial pressure of CO?
A) decreasing the partial pressure of H2O (g)
B) removing H2O (g) from the system
C) decreasing the volume of the reaction vessel
D) decreasing the pressure in the reaction vessel
E) increasing the amount of carbon in the system