Chapter 14 – Chemical Equilibrium
79. Select True or False: Consider the reaction N2(g) + 3H2(g) 2NH3(g). When hydrogen
gas is added to this system at equilibrium, the reaction will shift towards reactants.
80. Select True or False: Consider the reaction N2(g) + 3H2(g) 2NH3(g). When nitrogen is
added to the system at equilibrium, the reaction will shift toward the products.
81. Select True or False: Consider the reaction N2(g) + 3H2(g) 2NH3(g). When nitrogen is
removed from the system at equilibrium, the hydrogen (H2) concentration will increase.
Chapter 14 – Chemical Equilibrium
82. Select True or False: Consider the reaction N2(g) + 3H2(g) 2NH3(g). The production of
ammonia is an exothermic reaction. When heat is added to the equilibrium system it will shift
to increase the amount of ammonia produced.
83. Select True or False: Consider the reaction N2(g) + 3H2(g) 2NH3(g). Using a catalyst
will cause the reaction to shift to the right.
Chapter 14 – Chemical Equilibrium
84.
Select True or False: The following data for the reaction:
A(g) + 2B(s) AB2(g) provides evidence that the reaction is exothermic.
85.
Select True or False: Given the following data for the reaction: A(g) + 2B(s) AB2(g)
This data represents an endothermic reaction.
Chapter 14 – Chemical Equilibrium
86. Consider the reaction, N2(g) + 3H2(g) 2NH3(g). Kc = 8.1 x 10-3 at 900 K.
87. Consider the reaction, N2(g) + 3H2(g) 2NH3(g). Kc = 4.2 at 600 K.
What is the value of Kc for 4 NH3(g) 2N2(g) + 6H2(g)?
Chapter 14 – Chemical Equilibrium
88. 5.00 mol of ammonia are introduced into a 5.00 L reactor vessel in which it partially
dissociates at high temperatures.
2NH3(g) 3H2(g) + N2(g)
At equilibrium and a particular temperature, 1.00 mole of ammonia remains. Calculate Kc for
the reaction.
89. 4.2 mol of oxygen and 4.0 mol of NO are introduced to an evacuated 0.50 L reaction
vessel. At a specific temperature, the equilibrium 2NO(g) + O2(g) 2NO2(g) is reached
when [NO] = 1.6 M. Calculate Kc for the reaction at this temperature.
Chapter 14 – Chemical Equilibrium
90. 4.21 moles of S2Cl4 are introduced into a 2.0 L vessel.
S2Cl4(g) 2SCl2(g)
At equilibrium, 1.25 moles of S2Cl4 are found to remain in the container. Calculate Kc for this
reaction.
91.
The data below refer to the following reaction:
2NO(g) + Br2(g) 2NOBr(g)
Find the concentration of Br2 when the system reaches equilibrium.
Chapter 14 – Chemical Equilibrium
92.
The data below refer to the following reaction:
2NO(g) + Br2(g) 2NOBr(g)
Find the concentration of NOBr when the system reaches equilibrium.
Chapter 14 – Chemical Equilibrium
93.
The data below refer to the following reaction:
2NO(g) + Br2(g) 2NOBr(g)
Calculate Kc.
94. Consider the chemical reaction 2NH3(g) N2(g) + 3H2(g). The equilibrium is to be
established in a 1.0 L container at 1,000 K, where Kc = 4.0 10–2. Initially, 1,220 moles of
NH3(g) are present. Estimate the equilibrium concentration of H2(g).
Chapter 14 – Chemical Equilibrium
95. Consider the chemical reaction 2NH3(g) N2(g) + 3H2(g). The equilibrium is to be
established in a 1.0 L container at 1,000 K, where Kc = 4.0 10–2. Initially, 1,220 moles of
NH3(g) are present. Estimate the equilibrium concentration of N2(g).
96. Consider the chemical reaction 2NH3(g) N2(g) + 3H2(g). The equilibrium is to be
established in a 1.0 L container at 1,000 K, where Kc = 4.0 10–2. Initially, 1,220 moles of
NH3(g) are present. Calculate Kp for the reaction.
Chapter 14 – Chemical Equilibrium
97. Hydrogen iodide decomposes according to the equation:
2HI(g) H2(g) + I2(g), Kc = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of H2 equilibrium.
98. Hydrogen iodide decomposes according to the equation:
2HI(g) H2(g) + I2(g), Kc = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of HI at equilibrium.
Chapter 14 – Chemical Equilibrium
99. Select True or False: The conditions used in the Haber process to enhance the yield of
ammonia are low pressure and high temperature.
100.
Select True or False: Consider the equilibrium C(s) + H2O(g) CO(g) + H2(g), H = 2296 J. The concentration of carbon
monoxide will increase if the temperature of this system is raised.
101.
Select True or False: Consider the equilibrium C(s) + H2O(g) CO(g) + H2(g), H = 2296 J. The concentration of carbon
will not change if gaseous water is added to the system.
Chapter 14 – Chemical Equilibrium
102.
Select True or False: Consider the equilibrium equation C(s) + H2O(g) CO(g) + H2(g), H = 2296 J. The reaction will
shift towards products if the volume of the container is decreased.
103. Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon
dioxide as shown below.
CaCO3(s) CaO(s) + CO2(g)
The KP for this reaction is 1.16 at 800C. A 5.00 L vessel containing 10.0 g of CaCO3(s) was
evacuated to remove the air, sealed, and then heated to 800C. Ignoring the volume occupied
by the solid, what will be the mass of the solid in the vessel once equilibrium is reached?
Chapter 14 – Chemical Equilibrium
104. Calcium carbonate decomposes at high temperatures to give calcium oxide and carbon
dioxide as shown below.
CaCO3(s) CaO(s) + CO2(g)
The KP for this reaction is 1.16 at 800C. A 5.00 L vessel containing 10.0 g of CaCO3(s) was
evacuated to remove the air, sealed, and then heated to 800C. Ignoring the volume occupied
by the solid, what will be the overall mass percent of carbon in the solid once equilibrium is
reached?
105. What is the correct equilibrium constant expression for this reaction?
2HI(g) H2(g) + I2(g)
Chapter 14 – Chemical Equilibrium
106. Select True or False: Consider the following equilibrium:
4NH3(g) + 3O2(g) 2N2(g) + 6H2O(g) + 1531 kJ
107. Select True or False: Consider the following equilibrium:
4NH3(g) + 3O2(g) 2N2(g) + 6H2O(g) + 1531 kJ
108. Select True or False: Consider the following equilibrium:
4NH3(g) + 3O2(g) 2N2(g) + 6H2O(g) + 1531 kJ
Chapter 14 – Chemical Equilibrium
109. Select True or False: Consider the following equilibrium:
4NH3(g) + 3O2(g) 2N2(g) + 6H2O(g) + 1531 kJ
The concentrations the reactants would increase after nitrogen gas was removed from the
system.
110. The Kc for the reaction CO2(g) + H2(g) H2O(g) + CO(g) is 1.6 at about 990ºC.
Calculate the number of moles of carbon dioxide in the final equilibrium system obtained by
initially adding 1.00 mol of H2, 2.00 mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a
5.00 L reactor at 990ºC.
Chapter 14 – Chemical Equilibrium
111. The Kc for the reaction CO2(g) + H2(g) H2O(g) + CO(g) is 1.6 at about 990ºC.
Calculate the number of moles of hydrogen gas in the final equilibrium system obtained by
initially adding 1.00 mol of H2, 2.00 mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a
5.00 L reactor at 990ºC.
112. The Kc for the reaction CO2(g) + H2(g) H2O(g) + CO(g) is 1.6 at about 990ºC.
Calculate the number of moles of water in the final equilibrium system obtained by initially
adding 1.00 mol of H2, 2.00 mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00 L
reactor at 990ºC.
Chapter 14 – Chemical Equilibrium
113.
The Kc for the reaction CO2(g) + H2(g) H2O(g) + CO(g) is 1.6 at about 990ºC. Calculate the number of moles of carbon
monoxide in the final equilibrium system obtained by initially adding 1.00 mol of H2, 2.00 mol of CO2, 0.750 mol of H2O,
and 1.00 mol of CO to a 5.00 L reactor at 990ºC.
114. Two moles of PCl5 are placed in a 5.0 L container. Dissociation takes place according to
the equation PCl5(g) PCl3(g) + Cl2(g). At equilibrium, 0.40 mol of Cl2 are present.
Calculate the equilibrium constant (Kc) for this reaction under the conditions of this
experiment.
Chapter 14 – Chemical Equilibrium
115. Select True or False: The equilibrium between carbon dioxide gas and carbonic acid is
very important in biology and environmental science, and is shown below.
CO2(aq) + H2O(l) H2CO3(aq)
Based on the equilibrium constant reported for this reaction (Kc = 1.70 10–3), there will be
more carbon dioxide in solution than carbonic acid.
116. Select True or False: The equilibrium constant for the chemical equation
2NO(g) + O2(g) 2NO2(g)
is two times the equilibrium constant for the chemical equation
NO(g) + 1/2O2(g) NO2(g).
117. Select True or False: The equilibrium constant expression for the following reaction
CuO(s) + H2(g) Cu(s) + H2O(g) is Kc = [H2]/[H2O].
Chapter 14 – Chemical Equilibrium
118. Select True or False: When the reaction 2O3(g) 3O2(g), for which Kp = 3.0 1026 at
773ºC, is at equilibrium, the mixture will contain very little O2 as compared to O3.
119. Select True or False: Equilibrium constants are known for the following reactions:
S(s) + 3/2O2(g) SO3(g) Kc = 9.2 1023
SO3(g) SO2(g) + 1/2O2(g) Kc = 4.8 10– 4
Thus, for the reaction S(s) + O2(g) SO2(g), Kc = 4.4 1020.
120. Select True or False: For the reaction H2(g) + I2(g) 2HI(g), KP = Kc.