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Advanced Chemistry
Mr. Bennett
Chemical Equilibrium
Name_________________
MULTIPLE CHOICE QUESTIONS
1.
Which is the correct equilibrium constant expression for the following reaction?
Fe2O3(s) + 3H2(g)
2Fe(s) + 3H2O(g)
A. Kc = [Fe2O3] [H2]3 / [Fe]2[H2O]3
B. Kc = [H2] / [H2O]
C. Kc = [H2O]3 / [H2]3
2.
D.
E.
The equilibrium constant expression for the reaction 2BrF5(g)
The following reactions occur at 500 K. Arrange them in order of increasing tendency to
proceed to completion (least  greatest tendency).
1.
4.
Br2(g) + 5F2(g) is
D. Kc = [BrF5]2 / [Br2][F2]5
E. Kc = 2[BrF5]2 / ([Br2]  5[F2]5)
A. Kc =[Br2] [F2] / [BrF5]
B. Kc = [Br2] [F2]5 / [BrF5]2
C. Kc = [Br2] [F2]2 / [BrF5]5
3.
Kc = [Fe]2[H2O]3 / [Fe2O3] [H2]3
Kc = [Fe] [H2O] / [Fe2O3] [H2]
2NOCl
Kp = 1.7  10 2
2NO + Cl2
2. 2SO3
2SO2 + O2
3. 2NO2
A. 2 < 1 < 3
2NO + O2
B. 1 < 2 < 3
Kp = 1.3  10 5
Kp = 5.9  10 5
C. 2 < 3 < 1
D. 3 < 2 < 1
E. 3 < 1 < 2
Consider the two gaseous equilibria
SO2(g) + (1/2)O2(g)
2SO3(g)
SO3(g)
SO2(g) + O2(g)
K1
K2
The values of the equilibrium constants K1 and K2 are related by
A. K2 = K12
5.
B. K22 = K1
C. K2 = 1/K 1
2
D. K2 = 1/K1
E.
none of these.
Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic
gases, phosgene and chlorine.
CCl4(g) + (1/2)O2(g)
COCl2(g) + Cl2(g),
Calculate Kc for the reaction 2CCl4(g) + O2(g)
A. 4.4  109
D.
1.9  1019
9
B. 8.8  10
E.
2.3  1010
10
C. 1.9  10
Kc = 4.4  109 at 1,000 K
2COCl2(g) + 2Cl2(g).
1
6.
The equilibrium constant for the reaction Ni(s) + 4CO(g)
Ni(CO)4(g)
4
is 5.0  10 at 25ºC. What is the equilibrium constant for the reaction
Ni(CO)4(g)
A. 2.0  105
7.
Ni(s) + 4CO(g)?
B. 2.5  109
C. 5.0  104
D. 5.0  104
E. 2.0  103
Which of the following is a true statement about chemical equilibria in general?
A. At equilibrium the total concentration of products equals the total concentration of
reactants, that is, [products] = [reactants].
B. Equilibrium is the result of the cessation of all chemical change.
C. There is only one set of equilibrium concentrations that equals the K c value.
D. At equilibrium, the rate constant of the forward reaction is equal to the rate constant
for the reverse reaction.
E. At equilibrium, the rate of the forward reaction is equal to as the rate of the reverse
reaction.
8.
The following reactions occur at 500 K. Arrange them in order of increasing tendency to
proceed to completion (least completion greatest completion).
1) 2NOCl
2) N2O4
2NO2
Kp = 1.5  103
3) 2SO3
2SO2 + O2
Kp = 1.3  10 5
4) 2NO2
2NO + O2
Kp = 5.9  10 5
A. 2 < 1 < 3 < 4
9.
2NO + Cl2 Kp = 1.7  10 2
B. 3 < 1 < 4 < 2
D. 4 < 3 < 2 < 1
E. 4 < 3 < 1 < 2
When the following reaction is at equilibrium, which of these relationships is always true?
2NOCl(g)
2NO(g) + Cl2(g)
A. [NO] [Cl2] = [NOCl]
B. [NO]2 [Cl2] = [NOCl]2
C. [NOCl] = [NO]
10.
C. 3 < 4 < 1 < 2
D.
E.
2[NO] = [Cl2]
[NO]2 [Cl2] = Kc[NOCl]2
Calculate Kp for the reaction 2NOCl(g)
reaction is 2.1  102.
2NO(g) + Cl2(g) at 400C if Kc at 400C for this
A. 2.1  102
C. 0.70
B. 1.7  103
D. 1.2
E. 3.8  104
2
11.
On analysis, an equilibrium mixture for the reaction 2H 2S(g)
2H2(g) + S2(g) was found
to contain 1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the
equilibrium constant, Kc, for this reaction.
A. 1.6
12.
B. 3.2
C. 12.8
D. 0.64
E. 0.8
2.50 mol NOCl was placed in a 2.50 L reaction vessel at 400ºC. After equilibrium was
established, it was found that 28% of the NOCl had dissociated according to the equation
2NOCl(g)
2NO(g) + Cl2(g).
Calculate the equilibrium constant, Kc, for the reaction.
A. 0.021
13.
B. 0.039
A. 3.0  104
B. 1.8  103
C. 1.4  103
D. 5.6  104
E. 4.1  103
B. 5.1
C. 17
D. 19
E. 25
B. 0.125
C. 0.0750
D. 0.10
E. 0.050
Calculate Kc for the reaction 2HI(g)
H2(g) + I2(g) given that the concentrations of each
species at equilibrium are as follows:
[HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27 mol/L.
A. 5.25
17.
2NO(g) + Cl2(g).
The brown gas NO2 and the colorless gas N2O4 exist in equilibrium, 2NO2
N2O4. In an
experiment, 0.625 mole of N2O4 was introduced into a 5.00 L vessel and was allowed to
decompose until equilibrium was reached. The concentration of N2O4 at equilibrium was
0.0750 M. Calculate Kc for the reaction.
A. 7.5
16.
E. 47
The reaction A(g) + 2B(g)
C(g) was allowed to come to equilibrium. The initial amounts
of reactants placed into a 5.00 L vessel were 1.0 mol A and 1.8 mol B. After the reaction
reached equilibrium, 1.0 mol of B was found. Calculate K c for this reaction.
A. 0.060
15.
D. 26
1.25 moles of NOCl were placed in a 2.50 L reaction chamber at 427ºC. After equilibrium
was reached, 1.10 moles of NOCl remained. Calculate the equilibrium constant, K c, for the
reaction 2NOCl(g)
14.
C. 0.169
B. 0.22
C. 4.5
D. 0.19
E. 1.6  102
Phosgene, COCl2, a poisonous gas, decomposes according to the equation
COCl2(g)
A. 0.125
CO(g) + Cl2(g). Calculate Kp for this reaction if Kc = 0.083 at 900ºC.
B. 8.0
C. 6.1
D. 0.16
E. 0.083
3
18.
Kp for the reaction of SO2(g) with O2 to produce SO3(g) is 3  1024 . Calculate Kc for this
equilibrium at 25ºC. (The relevant reaction is 2SO2(g) + O2(g)
A. 3  1024
19.
B. 5  1021
C. 2  1020
2SO3(g).)
D. 5  1022
E. 7  1025
If one starts with pure NO2(g) at a pressure of 0.500 atm, the total pressure inside the
reaction vessel when 2NO2(g)
2NO(g) + O2(g) reaches equilibrium is 0.674 atm.
Calculate the equilibrium partial pressure of NO2.
A. 0.152 atm
B. 0.174 atm
C. 0.200 atm
D. 0.326 atm
E. The total pressure cannot be calculated because K p is not given
20.
Equilibrium is established for the reaction 2X(s) + Y(g)
2Z(g) at 500K, Kc = 100.
Determine the concentration of Z in equilibrium with 0.2 mol X and 0.50 M Y at 500K.
A. 3.2 M
21.
B. 3.5 M
B. 1.24 atm
C. 4.24 atm
D. 0.94 atm
E. 1.12 atm
B. 1.0  102 M
E. 1.6  103 M
C. 2.8  101 M
For the reaction SO2(g) + NO2(g)
SO3(g) + NO(g), the equilibrium constant is 18.0 at
1,200ºC. If 1.0 mole of SO2 and 2.0 moles of NO2 are placed in a 20. L container, what
concentration of SO3 will be present at equilibrium?
A. 0.48 mol/L
E. 18 mol/L
24.
E. None of these.
At 35ºC, the equilibrium constant for the reaction 2NOCl(g)
2NO(g) + Cl2(g) is
5
Kc = 1.6  10 . An equilibrium mixture was found to have the following concentrations of Cl2
and NOCl: [Cl2] = 1.2  102 M; [NOCl] = 2.8  101 M. Calculate the concentration of NO(g)
at equilibrium.
A. 1.0  104 M
D. 2.4  102 M
23.
D. 7.1 M
At 250ºC, the equilibrium constant Kp for the reaction PCl5(g)
PCl3(g) + Cl2(g) is 1.80.
Sufficient PCl5 is put into a reaction vessel to give an initial pressure of 2.74 atm at 250ºC.
Calculate the pressure of PCl5 after the system has reached equilibrium.
A. 1.50 atm
22.
C. 4.5 M
B. 0.11 mol/L
C. 0.95 mol/L
D. 2.22 mol/L
Consider the reaction N2(g) + O2(g)
2NO(g), for which Kc = 0.10 at 2,000ºC. Starting
with initial concentrations of 0.040 M of N2 and 0.040 M of O2, determine the equilibrium
concentration of NO.
A. 5.4  103 M
B. 0.0096 M
C. 0.011 M
D. 0.080 M
E. 0.10 M
4
25.
Hydrogen iodide decomposes according to the equation 2HI(g)
H2(g) + I2(g), for which
Kc = 0.0156 at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC.
Calculate the concentration of HI at equilibrium.
A. 0.138 M
26.
D. 0.275 M
E. 0.0275 M
B. 0.138 M
C. 0.0275 M
D. 0.0550 M
E. 0.220 M
At 400ºC, Kc = 64 for the equilibrium H2(g) + I2(g)
2HI(g). If 3.00 mol H2 and 3.00 mol
I2 are introduced into an empty 4.0 L vessel, find the equilibrium concentration of HI at
400ºC.
A. 0.15 M
28.
C. 0.550 M
Hydrogen iodide decomposes according to the equation 2HI(g)
H2(g) + I2(g), for which
Kc = 0.0156 at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC.
Calculate the concentration of H2 at equilibrium.
A. 0.275 M
27.
B. 0.220 M
B. 1.2 M
C. 2.4 M
D. 4.8 M
E. 5.8 M
Sodium carbonate, Na2CO3(s), can be prepared by heating sodium bicarbonate, NaHCO3(s).
2NaHCO3(s)
Na2CO3(s) + CO2(g) + H2O(g)
Kp = 0.23 at 100ºC
If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at
100ºC, what will the total gas pressure be?
A. 0.46 atm
29.
B. 0.96 atm
D. 0.48 atm
E. 0.11 atm
For the nitrogen fixation reaction 3H2(g) + N2(g)
2NH3(g), Kc = 6.0  102 at 500C. If
0.250 M H2 and 0.050 M NH3 are present at equilibrium, what is the equilibrium
concentration of N2?
A. 0.750 M
30.
C. 0.23 atm
B. 2.7 M
C. 0.250 M
D. 0.025 M
E. 1.85 M
For the following reactions the equilibrium constants are defined as follows:
A + 2B
C
C K1
D+E
K2
For the reaction A + 2B
A. Kc = K1 + K2
D. Kc = (K1)(K2)
D + E, having equilibrium constant Kc,
B. Kc = K1/K2
E. Kc = K2/K1
C. Kc = K1 – K2
5
31.
Consider the following equilibria:
2SO3(g)
2SO2(g) + O2(g)
Kc = 2.3  107
2NO3(g)
2NO2(g) + O2(g) Kc = 1.4  103
Calculate the equilibrium constant for the reaction
SO2(g) + NO3(g)
A. 78
32.
B. 1.3  102
SO3(g) + NO2(g).
C. 1.6  104
D. 3.2  1010
E. 6.1  103
At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium constant Kc = 4.3 
6
10 , and the following concentrations are present: [SO2] = 0.10 M; [SO3] = 10. M; [O2] =
0.10 M.
Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is
written), left to right or right to left, will the reaction proceed to reach equilibrium?
A.
B.
C.
D.
33.
Yes, the mixture is at equilibrium.
No, left to right
No, right to left
There is not enough information to be able to predict the direction.
At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium constant Kc = 4.3
 106, and the following concentrations are present: [SO2] = 0.010 M; [SO3] = 10. M; [O2]
= 0.010 M.
Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is
written), left to right or right to left, will the reaction proceed to reach equilibrium?
A. Yes, the mixture is at equilibrium.
B.. No, left to right
C. No, right to left
D. There is not enough information to be able to predict the direction.
34.
For the reaction H2(g) + I2(g)
2HI(g), Kc = 50.2 at 445ºC. If [H2] = [I2] = [HI] = 1.75 
103 M at 445ºC, which one of the following statements is true?
A.
B.
C.
D.
E.
The system is at equilibrium, thus no concentration changes will occur.
The concentrations of HI and I2 will increase as the system approaches equilibrium.
The concentration of HI will increase as the system approaches equilibrium.
The concentrations of H2 and HI will fall as the system moves toward equilibrium.
The concentrations of H2 and I2 will increase as the system approaches equilibrium.
6
35.
For the reaction PCl3(g) + Cl2(g)
PCl5(g) at a particular temperature, Kc = 24.3.
Suppose a system at that temperature is prepared with [PCl 3] = 0.10 M, [Cl2] = 0.15 M, and
[PCl5] = 0.60 M. Which of the following statements is true?
A. The reaction is at equilibrium.
B. The reaction will proceed in the direction of forming more PCl 5 until equilibrium is
reached.
C. The reaction will proceed in the direction of forming more PCl 3 and Cl2 until
equilibrium is reached.
D. None of the above statements is true.
36.
For the following reaction at equilibrium, which choice gives a change that will shift the
position of equilibrium to favor formation of more products?
2NOBr(g)
2NO(g) + Br2(g),
Hºrxn = 30 kJ/mol
A. Increase the total pressure by decreasing the volume.
B. Add more NO.
C. Remove Br2.
D. Lower the temperature.
E. Remove NOBr selectively.
37.
For the following reaction at equilibrium, which one of the changes below would cause the
equilibrium to shift to the left?
2NOBr(g)
2NO(g) + Br2(g),
A. Increase the container volume.
B. Remove some NO.
C. Remove some Br2 .
38.
D.
E.
Add more NOBr.
Decrease the temperature.
For the following reaction at equilibrium in a reaction vessel, which one of the changes below
would cause the Br2 concentration to decrease?
2NOBr(g)
2NO(g) + Br2(g),
A. Increase the temperature.
B. Remove some NO.
39.
Hºrxn = 30 kJ/mol
C.
D.
Hºrxn= 30 kJ/mol
Add more NOBr.
Compress the gas mixture into a smaller volume.
For the following reaction at equilibrium in a reaction vessel, which one of the changes below
would cause the Br2 concentration to increase?
2NOBr(g)
2NO(g) + Br2(g),
Hºrxn= 30 kJ/mol
A. Lower the temperature.
B.
Remove some NO.
C.
D. Compress the gas mixture into a smaller volume.
Remove some NOBr.
7
40.
For the equilibrium reaction 2SO2(g) + O2(g)
2SO3(g), Hºrxn = 198 kJ/mol. Which
one of the following factors would cause the equilibrium constant to increase?
A. Decrease the temperature.
B. Add SO2 gas.
C. Remove O2 gas.
41.
The reaction 2SO3(g)
increased,
Add a catalyst.
None of these.
2SO2(g) + O2(g) is endothermic. If the temperature is
A. more SO3 will be produced.
D. Kc will increase.
42.
D.
E.
B. Kc will decrease.
C. no change will occur in Kc .
E. the pressure will decrease.
For the reaction at equilibrium 2SO3
2SO2 + O2 (Hºrxn= 198 kJ/mol), if we increase
the reaction temperature, the equilibrium will
A. shift to the right.
B. shift to the left.
C. not shift.
D. The question cannot be answered because the equilibrium constant is not given.
43.
Which of the following will result if some CH4(g) is removed from the reaction
CO(g) + 3H2(g)
CH4(g) + H2O(g) at equilibrium?
A. H2O will be consumed.
B. More CH4 and H2O will be produced.
C. Kp will decrease.
44.
45.
D.
E.
More CO will be produced.
No change will occur.
In which of the following gas-phase equilibria is the yield of products increased by
increasing the total pressure on the reaction mixture?
A. CO(g) + H2O(g)
CO2(g) + H2(g)
C.
2SO3(g)
B. 2NO(g) + Cl2(g)
2NOCl(g)
D.
PCl5(g)
2SO2(g) + O2(g)
PCl3(g) + Cl2(g)
Consider the following gas phase equilibrium system:
PCl5(g)
PCl3(g) + Cl2(g)
Hºrxn = +87.8 kJ/mol.
Which of the following statements is false?
A. Increasing the system volume shifts the equilibrium to the right.
B. Increasing the temperature shifts the equilibrium to the right.
C. A catalyst speeds up the approach to equilibrium and shifts the position of equilibrium
to the right.
D. Decreasing the total pressure of the system shifts the equilibrium to the right.
E. Increasing the temperature causes the equilibrium constant to increase.
8
46.
The reaction 2NO(g)
N2(g) + O2(g) is exothermic, Hºrxn = 180 kJ/mol.
Which one of the following statements is true?
A.
B.
C.
D.
47.
Kp at 1,000 K is less than Kp at 2,000 K.
Kp at 1,000 K is larger than Kp at 2,000 K.
The Kp's at 1000 K and 2000 K are the same.
Kp depends on total pressure as well as temperature.
Consider the following reaction at equilibrium:
2SO2(g) + O2(g)
2SO3(g),
Hºrxn = 198 kJ/mol
If the volume of the system is compressed at constant temperature, what change will occur
in the position of the equilibrium?
A. A shift to produce more SO2
B. A shift to produce more O2
48.
C. No change
D. A shift to produce more SO3
Consider the following reaction at equilibrium at a total pressure P 1:
2SO2(g) + O2(g)
2SO3(g)
Suppose the volume of this system is compressed to one-half its initial volume and then
equilibrium is reestablished. The new equilibrium total pressure will be
A. twice P1
B. three times P1
C. 3.5 P1
49.
For the reaction 2NOCl(g)
D. less than twice P1
E. unchanged
2NO(g) + Cl2(g), Kc = 8.0 at a certain temperature.
What concentration of NOCl must be put into an empty 4.00 L reaction vessel in order that
the equilibrium concentration of NOCl be 1.00 M?
A. 1.26 M
50.
B. 2.25 M
C. 2.50 M
D. 3.52 M
E. 11.0 M
The equilibrium constants (expressed in atm) for the chemical reaction
N2(g) + O2(g)
2NO(g) are Kp = 1.1  103 and 3.6  103 at 2,200 K and 2,500 K,
respectively. Which one of the following statements is true?
A.
B.
C.
D.
E.
The reaction is exothermic, Hº < 0.
The partial pressure of NO(g) is less at 2,200 K than at 2,500 K.
Kp is less than Kc by a factor of (RT).
The total pressure at 2,200 K is the same as at 2,500 K.
Higher total pressure shifts the equilibrium to the left.
9
51.
When the substances in the equation below are at equilibrium, at pressure P and
temperature T, the equilibrium can be shifted to favor the products by
CuO(s) + H2(g)
A.
B.
C.
D.
E.
52.
H2O(g) + Cu(s)
Hºrxn = 2.0 kJ/mol
increasing the pressure by means of a moving piston at constant T.
increasing the pressure by adding an inert gas such as nitrogen.
decreasing the temperature.
allowing some gases to escape at constant P and T.
adding a catalyst.
50.0 g of N2O4 is introduced into an evacuated 2.00 L vessel and allowed to come to
equilibrium with its decomposition product, N2O4(g)
2NO2(g). For this reaction
Kc = 0.133. Once the system has reached equilibrium, 5.00 g of NO 2 is injected into the
vessel, and the system is allowed to equilibrate once again. Calculate the mass of NO 2 in the
final equilibrium mixture.
A. 17.8 g
53.
B. 12.4 g
C. 14.7 g
D. 19.7 g
E. 15.5 g
50.0 g of N2O4 is introduced into an evacuated 2.00 L vessel and allowed to come to
equilibrium with its decomposition product, N2O4(g)
2NO2(g). For this reaction
Kc = 0.133. Once the system has reached equilibrium, 5.00 g of NO 2 is injected into the
vessel, and the system is allowed to equilibrate once again. Calculate the mass of N2O4 in
the final equilibrium mixture.
A. 39.5 g
54.
B. 35.3 g
C. 30.3 g
D. 25.2 g
E. 43.7 g
75.0 g of PCl5(g) is introduced into an evacuated 3.00 L vessel and allowed to reach
equilibrium at 250ºC.
PCl5(g)
PCl3(g) + Cl2(g)
If Kp = 1.80 for this reaction, what is the total pressure inside the vessel at equilibrium.
A. 2.88 atm
55.
B. 2.27 atm
C. 4.54 atm
D. 7.42 atm
E. 9.69 atm
75.0 g of PCl5(g) is introduced into a 3.00 L vessel containing 10.0 g of Cl 2(g), and the system
is allowed to reach equilibrium at 250ºC.
PCl5(g)
PCl3(g) + Cl2(g)
If Kp = 1.80 for this reaction, what is the total pressure inside the vessel at equilibrium.
A. 6.83 atm
B. 8.85 atm
C. 5.38 atm
D. 3.47 atm
E. 7.42 atm
10
56.
25.0 g of HI(g) is injected into a 4.00 L reaction vessel that contains 20.0 g of I 2(g). When
the system comes to equilibrium at 400ºC, what will be the total pressure inside the
reaction vessel?
2HI(g)
A. 2.70 atm
B. 13.0 atm
H2(g) + I2(g),
C. 2.43 atm
Kc = 0.0156 at 400ºC
D. 0.815 atm
E. 3.24 atm
SHORT ANSWER QUESTIONS
57.
Describe why addition of a catalyst does not affect the equilibrium constant for a
reaction.
58.
Consider the reaction N2(g) + 3H2(g)
2NH3(g).
a. If hydrogen gas is added to the above system at equilibrium, which direction will the
reaction shift?
b. If nitrogen is added to the system at equilibrium, what will happen to the ammonia
concentration?
c. If nitrogen is removed from the system at equilibrium, what will happen to the
hydrogen (H2) concentration?
d. The production of ammonia is an endothermic reaction. Will heating the equilibrium
system increase or decrease the amount of ammonia produced?
e. If we use a catalyst, which way will the reaction shift?
59.
5.00 mol of ammonia are introduced into a 5.00 L reactor vessel in which it partially
dissociates at high temperatures.
2NH3(g)
60.
3H2(g) + N2(g)
At equilibrium at a particular temperature, 1.00 mole of ammonia remains. Calculate K c for
the reaction.
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?
61.
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 K c for
this reaction.
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62.
a. Fill in the table below, which refers to the following reaction:
2NO(g) + Br2(g)
2NOBr(g)
Concentration (M)
[NO]
Initial
Change
Equilibrium
2.5
____
2.0
[Br2]
5.0
____
____
[NOBr]
1.0
____
____
b. Calculate Kc.
63.
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.
a. Estimate the equilibrium concentration of H2(g).
b. Estimate the equilibrium concentration of N2(g).
c. Calculate Kp for the reaction.
64.
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 concentrations of H2 and HI at equilibrium.
65.
What conditions are used in the Haber process to enhance the yield of ammonia?
Explain why each condition affects the yield in terms of the Le Châtelier principle.
66.
The dissociation of solid silver chloride in water to produce silver ions and chloride ions
has an equilibrium constant of 1.8 x1018. Based on the magnitude of the equilibrium
constant, is silver chloride very soluble in water? Why?
67.
Consider the equilibrium equation C(s) + H2O(g) + 2296 J
CO(g) + H2(g).
a.
What will happen to the concentration of carbon monoxide if the temperature of
this system is raised?
b. If additional gaseous water is added to this reaction mixture, what will happen
to the temperature of the mixture?
c. What will happen to the mass of carbon if we add water to the system?
d. Which way will the reaction shift if the pressure on the system is increased?
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68.
Ethanol and acetic acid react to form ethyl acetate and water according to the equation
C2H5OH + CH3COOH
CH3COOC2H5 + H2O
When two moles each of ethanol and acetic acid are allowed to react at 100ºC in a sealed
tube, equilibrium is established when two-thirds of a mole of each of the reactants remains.
Calculate the equilibrium constant for this reaction.
69.
5.00 mol each of acetic acid and ethanol are allowed to react in a 1.00 L sealed container at
100ºC until equilibrium is established. How many moles of the ester and water are produced
and how many moles of ethanol and acid remain? The equilibrium constant is 4.00 for this
reaction,
C2H5OH + CH3COOH
70.
What is the correct equilibrium constant expression for the following reaction?
2HI(g)
71.
CH3COOC2H5 + H2O.
H2(g) + I2(g)
Consider the following equilibrium,
4NH3 + 3O2
2 N2 + 6H2O + 1531 kJ
a.
State whether the concentration of each of the reactants and products would increase,
decrease, or remain constant when the temperature is increased.
b. State whether the concentration of each of the reactants and products would increase,
decrease, or remain constant when 2 mol of ammonia are added to the system.
72.
Kc for the reaction CO2(g) + H2(g)
H2O(g) + CO(g) is 1.6 at about 990ºC.
Calculate the number of moles of each component in the final equilibrium system obtained
from adding 1.00 mol of H 2 , 2.00 mol of CO2 , 0.750 mol of H2O, and 1.00 mol of CO to a
5.00 L reactor at 990ºC.
73.
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.
TRUE-FALSE QUESTIONS
74.
The equilibrium constant expression for the reaction
CuO(s) + H2(g)
75.
Cu(s) + H2O(g) is Kc = [H2]/[H2O].
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.
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76.
If the system 3H2(g) + N2(g)
2NH3(g) is at equilibrium and more N2 is added, a net
reaction that consumes some of the added N2 will occur until a new equilibrium is reached.
77.
Equilibrium constants are known for the following reactions:
S(s) + (3/2)O2(g)
SO3(g)
SO2(g) + (1/2)O2(g)
Thus, for the reaction S(s) + O2(g)
78.
Kc = 9.2  1023
SO3(g)
For the reaction H2(g) + I2(g)
Kc = 4.8  10 4
SO2(g), Kc = 4.4  1020.
2HI(g), Kp = Kc.
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