Download Chapter 14 Review

Chapter 14 Review
Student: ___________________________________________________________________________
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
D. Kc = [Fe]2[H2O]3/[Fe2O3] [H2]3
E. Kc = [Fe] [H2O]/[Fe2O3] [H2]
2.
The equilibrium constant expression for the reaction 2BrF5(g)
A. Kc =[Br2] [F2]/[BrF5]
B. Kc = [Br2] [F2]5/[BrF5]2
C. Kc = [Br2] [F2]2/[BrF5]5
D. Kc = [BrF5]2/[Br2][F2]5
E. Kc = 2[BrF5]2/([Br2] × 5[F2]5)
Br2(g) + 5F2(g) is
3.
Consider the two gaseous equilibria
The values of the equilibrium constants K1 and K2 are related by
A. K2 = K12
B. K22 = K1
C. K2 = 1/K12
D. K2 = 1/K1
E. none of these
4.
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), Kc = 4.4 × 109 at 1,000 K
Calculate Kc for the reaction 2CCl4(g) + O2(g)
A. 4.4 × 109
B. 8.8 × 109
C. 1.9 × 1010
D. 1.9 × 1019
E. 2.3 × 10-10
2COCl2(g) + 2Cl2(g).
5.
Which of these statements is true 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 Kc 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.
6.
The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least
completion greatest completion).
A. 2 < 1 < 3 < 4
B. 3 < 1 < 4 < 2
C. 3 < 4 < 1 < 2
D. 4 < 3 < 2 < 1
E. 4 < 3 < 1 < 2
7.
Calculate Kp for the reaction 2NOCl(g)
A. 2.1 × 10-2
B. 1.7 × 10-3
C. 0.70
D. 1.2
E. 3.8 × 10-4
2NO(g) + Cl2(g) at 400°C if Kc at 400°C for this reaction is 2.1 × 10-2.
8.
On analysis, an equilibrium mixture for the reaction 2H2S(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
B. 3.2
C. 12.8
D. 0.64
E. 0.8
9.
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
B. 0.039
C. 0.169
D. 26
E. 47
10. 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, Kc, for the reaction 2NOCl(g)
A. 3.0 × 10-4
B. 1.8 × 103
C. 1.4 × 10-3
D. 5.6 × 10-4
E. 4.1 × 10-3
2NO(g) + Cl2(g).
11. 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 Kc for this
reaction.
A. 0.060
B. 5.1
C. 17
D. 19
E. 25
12. The brown gas NO and the colorless gas N O exist in equilibrium, 2NO
N2O4. In an experiment, 0.625 mole of N2O4
2
2 4
2
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
B. 0.125
C. 0.0750
D. 0.10
E. 0.050
13. Phosgene, COCl2, a poisonous gas, decomposes according to the equation
COCl2(g)
A. 0.125
B. 8.0
C. 6.1
D. 0.16
E. 0.083
CO(g) + Cl2(g). Calculate Kp for this reaction if Kc = 0.083 at 900ºC.
14. Calculate K for the reaction 2HI(g)
H2(g) + I2(g) given that the concentrations of each species at equilibrium are as
c
follows:
[HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27 mol/L.
A. 5.25
B. 0.22
C. 4.5
D. 0.19
E. 1.6 × 102
15. 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
B. 5 × 1021
C. 2 × 1020
D. 5 × 1022
E. 7 × 1025
2SO3(g).)
16. If one starts with pure NO (g) at a pressure of 0.500 atm, the total pressure inside the reaction vessel when 2NO (g)
2
2
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 Kp is not given.
17. At 250ºC, the equilibrium constant K for the reaction PCl (g)
PCl3(g) + Cl2(g) is 1.80. Sufficient PCl5 is put into a
p
5
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
B. 1.24 atm
C. 4.24 atm
D. 0.94 atm
E. 1.12 atm
18. Consider the reaction N (g) + O (g)
2NO(g), for which Kc = 0.10 at 2,000ºC. Starting with initial concentrations of 0.040
2
2
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
19. 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
B. 0.220 M
C. 0.550 M
D. 0.275 M
E. 0.0275 M
20. 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
B. 0.96 atm
C. 0.23 atm
D. 0.48 atm
E. 0.11 atm
21. 15.00 g of solid ammonium hydrogen sulfide is introduced into a 500.-mL flask at 25°C, the flask is sealed, and the system is
allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp = 0.108 at 25°C for NH4HS(s)
NH3(g) + H2S (g)?
A. 0.657 atm
B. 1.25 atm
C. 0.329 atm
D. 14.4 atm
E. 2.50 atm
22. At 340 K, K = 69 for the reaction H (g) + I (g)
2HI(g). 50.0 g of HI is injected into an evacuated 5.00-L rigid cylinder
p
2
2
at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium?
A. 2.60 atm
B. 1.76 atm
C. 0.424 atm
D. 2.18 atm
E. 10.9 atm
23. For the nitrogen fixation reaction 3H (g) + N (g)
2NH3(g), Kc = 6.0 × 10-2 at 500°C. If 0.250 M H2 and 0.050 M NH3
2
2
are present at equilibrium, what is the equilibrium concentration of N2?
A. 0.750 M
B. 2.7 M
C. 0.250 M
D. 0.025 M
E. 1.85 M
24.
Consider the following reactions and their associated equilibrium constants:
For the reaction A + 2B
A. Kc = K1
+ K2
B. Kc = K1/K2
C. Kc =
K 1 - K2
D. Kc = (K1)(K2)
E. Kc = K2/K1
D + E, having equilibrium constant Kc,
25. At 700 K, the reaction 2SO (g) + O (g)
2SO3(g) has the equilibrium constant Kc = 4.3 × 106, and the following
2
2
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. 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.
26. At 700 K, the reaction 2SO (g) + O (g)
2SO3(g) has the equilibrium constant Kc = 4.3 × 106, and the following
2
2
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.
27. For the reaction H (g) + I (g)
2HI(g), Kc = 50.2 at 445ºC. If [H2] = [I2] = [HI] = 1.75 × 10-3 M at 445ºC, which one of
2
2
these statements is true?
A. The system is at equilibrium, thus no concentration changes will occur.
B. The concentrations of HI and I2 will increase as the system approaches equilibrium.
C. The concentration of HI will increase as the system approaches equilibrium.
D. The concentrations of H2 and HI will fall as the system moves toward equilibrium.
E. The concentrations of H2 and I2 will increase as the system approaches equilibrium.
28. 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.
29. 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), Hºrxn = 30 kJ/mol
A. Increase the container volume.
B. Remove some NO.
C. Remove some Br2 .
D. Add more NOBr.
E. Decrease the temperature.
30. For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2 concentration to
decrease?
A.
B.
C.
D.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Increase the temperature.
Remove some NO.
Add more NOBr.
Compress the gas mixture into a smaller volume.
31. For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2 concentration to
increase?
A.
B.
C.
D.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Lower the temperature.
Remove some NO.
Remove some NOBr.
Compress the gas mixture into a smaller volume.
32. For the equilibrium reaction 2SO (g) + O (g)
2
2
the equilibrium constant to increase?
A. Decrease the temperature.
B. Add SO2 gas.
C. Remove O2 gas.
D. Add a catalyst.
E. none of these
2SO3(g), Hºrxn = -198 kJ/mol. Which one of these factors would cause
33. The reaction 2SO (g)
2SO2(g) + O2(g) is endothermic. If the temperature is increased,
3
A. more SO3 will be produced.
B. Kc will decrease.
C. no change will occur in Kc .
D. Kc will increase.
E. the pressure will decrease.
34. For the reaction at equilibrium 2SO
2SO2 + O2 ( Hºrxn= 198 kJ/mol), if we increase the reaction temperature, the
3
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.
35. Which of these situations 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.
D. More CO will be produced.
E. No change will occur.
36. In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on the reaction
mixture?
A. CO(g) + H O(g)
CO (g) + H (g)
2
2
B. 2NO(g) + Cl (g)
2NOCl(g)
2
C. 2SO (g)
2SO
(g)
+ O2(g)
3
2
D. PCl (g)
PCl (g) + Cl (g)
5
3
2
2
37. Consider this gas phase equilibrium system:
PCl5(g)
PCl3(g) + Cl2(g) Hºrxn = +87.8 kJ/mol.
Which of these 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.
38. The reaction 2NO(g)
N2(g) + O2(g) is exothermic, Hºrxn = -180 kJ/mol.
Which one of these statements is true?
A. Kp at 1,000 K is less than Kp at 2,000 K.
B. Kp at 1,000 K is larger than Kp at 2,000 K.
C. The Kp's at 1000 K and 2000 K are the same.
D. Kp depends on total pressure as well as temperature.
39. 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 NO2
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
B. 35.3 g
C. 30.3 g
D. 25.2 g
E. 43.7 g
40. Describe why addition of a catalyst does not affect the equilibrium constant for a reaction.
41. 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.
42. 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?
Chapter 14 Review Key
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
D. Kc = [Fe]2[H2O]3/[Fe2O3] [H2]3
E. Kc = [Fe] [H2O]/[Fe2O3] [H2]
Difficulty: Easy
Raymond - 014 Chemical... #1
2.
The equilibrium constant expression for the reaction 2BrF5(g)
A. Kc =[Br2] [F2]/[BrF5]
B. Kc = [Br2] [F2]5/[BrF5]2
C. Kc = [Br2] [F2]2/[BrF5]5
D. Kc = [BrF5]2/[Br2][F2]5
E. Kc = 2[BrF5]2/([Br2] × 5[F2]5)
Br2(g) + 5F2(g) is
Difficulty: Easy
Raymond - 014 Chemical... #2
3.
Consider the two gaseous equilibria
The values of the equilibrium constants K1 and K2 are related by
A. K2 = K12
B. K22 = K1
C. K2 = 1/K12
D. K2 = 1/K1
E. none of these
Difficulty: Medium
Raymond - 014 Chemical... #4
4.
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), Kc = 4.4 × 109 at 1,000 K
Calculate Kc for the reaction 2CCl4(g) + O2(g)
A. 4.4 × 109
B. 8.8 × 109
C. 1.9 × 1010
D. 1.9 × 1019
E. 2.3 × 10-10
2COCl2(g) + 2Cl2(g).
Difficulty: Medium
Raymond - 014 Chemical... #5
5.
Which of these statements is true 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 Kc 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.
Difficulty: Medium
Raymond - 014 Chemical... #7
6.
The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least
completion greatest completion).
A.
B.
C.
D.
E.
2<1<3<4
3<1<4<2
3<4<1<2
4<3<2<1
4<3<1<2
Difficulty: Medium
Raymond - 014 Chemical... #8
7.
Calculate Kp for the reaction 2NOCl(g)
A. 2.1 × 10-2
B. 1.7 × 10-3
C. 0.70
D. 1.2
E. 3.8 × 10-4
2NO(g) + Cl2(g) at 400°C if Kc at 400°C for this reaction is 2.1 × 10-2.
Difficulty: Medium
Raymond - 014 Chemical... #10
8.
On analysis, an equilibrium mixture for the reaction 2H2S(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
B. 3.2
C. 12.8
D. 0.64
E. 0.8
Difficulty: Medium
Raymond - 014 Chemical... #11
9.
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
B. 0.039
C. 0.169
D. 26
E. 47
Difficulty: Medium
Raymond - 014 Chemical... #12
10.
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, Kc, for the reaction 2NOCl(g)
A. 3.0 × 10-4
B. 1.8 × 103
C. 1.4 × 10-3
D. 5.6 × 10-4
E. 4.1 × 10-3
2NO(g) + Cl2(g).
Difficulty: Medium
Raymond - 014 Chemical... #13
11.
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 Kc
for this reaction.
A. 0.060
B. 5.1
C. 17
D. 19
E. 25
Difficulty: Medium
Raymond - 014 Chemical... #14
12.
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
B. 0.125
C. 0.0750
D. 0.10
E. 0.050
Difficulty: Medium
Raymond - 014 Chemical... #15
13.
Phosgene, COCl2, a poisonous gas, decomposes according to the equation
COCl2(g)
A. 0.125
B. 8.0
C. 6.1
D. 0.16
E. 0.083
CO(g) + Cl2(g). Calculate Kp for this reaction if Kc = 0.083 at 900ºC.
Difficulty: Medium
Raymond - 014 Chemical... #17
14.
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
B. 0.22
C. 4.5
D. 0.19
E. 1.6 × 102
Difficulty: Medium
Raymond - 014 Chemical... #16
15.
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
B. 5 × 1021
C. 2 × 1020
D. 5 × 1022
E. 7 × 1025
2SO3(g).)
Difficulty: Medium
Raymond - 014 Chemical... #18
16.
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 Kp is not given.
Difficulty: Medium
Raymond - 014 Chemical... #19
17.
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
B. 1.24 atm
C. 4.24 atm
D. 0.94 atm
E. 1.12 atm
Difficulty: Medium
Raymond - 014 Chemical... #21
18.
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
Difficulty: Medium
Raymond - 014 Chemical... #24
19.
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
B. 0.220 M
C. 0.550 M
D. 0.275 M
E. 0.0275 M
Difficulty: Medium
Raymond - 014 Chemical... #25
20.
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
B. 0.96 atm
C. 0.23 atm
D. 0.48 atm
E. 0.11 atm
Difficulty: Medium
Raymond - 014 Chemical... #28
21.
15.00 g of solid ammonium hydrogen sulfide is introduced into a 500.-mL flask at 25°C, the flask is sealed, and the system
is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp = 0.108 at 25°C for NH4HS(s)
A.
B.
C.
D.
E.
NH3(g) + H2S (g)?
0.657 atm
1.25 atm
0.329 atm
14.4 atm
2.50 atm
Difficulty: Medium
Raymond - 014 Chemical... #30
22.
At 340 K, Kp = 69 for the reaction H2(g) + I2(g)
2HI(g). 50.0 g of HI is injected into an evacuated 5.00-L rigid
cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to equilibrium?
A. 2.60 atm
B. 1.76 atm
C. 0.424 atm
D. 2.18 atm
E. 10.9 atm
Difficulty: Medium
Raymond - 014 Chemical... #29
23.
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
B. 2.7 M
C. 0.250 M
D. 0.025 M
E. 1.85 M
Difficulty: Medium
Raymond - 014 Chemical... #31
24.
Consider the following reactions and their associated equilibrium constants:
For the reaction A + 2B
A. Kc = K1
+ K2
B. Kc = K1/K2
C. Kc =
K1 - K2
D. Kc = (K1)(K2)
E. Kc = K2/K1
D + E, having equilibrium constant Kc,
Difficulty: Medium
Raymond - 014 Chemical... #32
25.
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] = 0.10 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. 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.
26.
Difficulty: Medium
Raymond - 014 Chemical... #34
6
At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium constant Kc = 4.3 × 10 , 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.
27.
For the reaction H2(g) + I2(g)
2HI(g), Kc = 50.2 at 445ºC. If [H2] = [I2] = [HI] = 1.75 ×
of these statements is true?
A. The system is at equilibrium, thus no concentration changes will occur.
B. The concentrations of HI and I2 will increase as the system approaches equilibrium.
C. The concentration of HI will increase as the system approaches equilibrium.
D. The concentrations of H2 and HI will fall as the system moves toward equilibrium.
E. The concentrations of H2 and I2 will increase as the system approaches equilibrium.
Difficulty: Medium
Raymond - 014 Chemical... #35
10-3 M at 445ºC, which one
Difficulty: Medium
Raymond - 014 Chemical... #36
28.
For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor
formation of more products?
A.
B.
C.
D.
E.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn = 30 kJ/mol
Increase the total pressure by decreasing the volume.
Add more NO.
Remove Br2.
Lower the temperature.
Remove NOBr selectively.
Difficulty: Medium
Raymond - 014 Chemical... #38
29.
For the following reaction at equilibrium, which one of the changes below would cause the equilibrium to shift to the left?
A.
B.
C.
D.
E.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn = 30 kJ/mol
Increase the container volume.
Remove some NO.
Remove some Br2 .
Add more NOBr.
Decrease the temperature.
Difficulty: Medium
Raymond - 014 Chemical... #39
30.
For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2
concentration to decrease?
A.
B.
C.
D.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Increase the temperature.
Remove some NO.
Add more NOBr.
Compress the gas mixture into a smaller volume.
Difficulty: Medium
Raymond - 014 Chemical... #40
31.
For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2
concentration to increase?
A.
B.
C.
D.
2NOBr(g)
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Lower the temperature.
Remove some NO.
Remove some NOBr.
Compress the gas mixture into a smaller volume.
Difficulty: Medium
Raymond - 014 Chemical... #41
32.
For the equilibrium reaction 2SO2(g) + O2(g)
cause the equilibrium constant to increase?
A. Decrease the temperature.
B. Add SO2 gas.
C. Remove O2 gas.
D. Add a catalyst.
E. none of these
2SO3(g), Hºrxn = -198 kJ/mol. Which one of these factors would
Difficulty: Medium
Raymond - 014 Chemical... #42
33.
The reaction 2SO3(g)
2SO2(g) + O2(g) is endothermic. If the temperature is increased,
A. more SO3 will be produced.
B. Kc will decrease.
C. no change will occur in Kc .
D. Kc will increase.
E. the pressure will decrease.
Difficulty: Medium
Raymond - 014 Chemical... #43
34.
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.
Difficulty: Medium
Raymond - 014 Chemical... #44
35.
Which of these situations 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.
D. More CO will be produced.
E. No change will occur.
Difficulty: Medium
Raymond - 014 Chemical... #45
36.
In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on the reaction
mixture?
A. CO(g) + H O(g)
CO (g) + H (g)
2
2
B. 2NO(g) + Cl (g)
2NOCl(g)
2
C. 2SO (g)
2SO
(g)
+ O2(g)
3
2
D. PCl (g)
PCl (g) + Cl (g)
5
3
2
2
Difficulty: Medium
Raymond - 014 Chemical... #47
37.
Consider this gas phase equilibrium system:
PCl5(g)
PCl3(g) + Cl2(g) Hºrxn = +87.8 kJ/mol.
Which of these 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.
Difficulty: Medium
Raymond - 014 Chemical... #48
38.
The reaction 2NO(g)
N2(g) + O2(g) is exothermic, Hºrxn = -180 kJ/mol.
Which one of these statements is true?
A. Kp at 1,000 K is less than Kp at 2,000 K.
B. Kp at 1,000 K is larger than Kp at 2,000 K.
C. The Kp's at 1000 K and 2000 K are the same.
D. Kp depends on total pressure as well as temperature.
Difficulty: Medium
Raymond - 014 Chemical... #49
39.
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 NO2
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
B. 35.3 g
C. 30.3 g
D. 25.2 g
E. 43.7 g
Difficulty: Difficult
Raymond - 014 Chemical... #56
40.
Describe why addition of a catalyst does not affect the equilibrium constant for a reaction.
A catalyst affects both the forward and reverse rate of the reaction. Therefore, the equilibrium constant is not affected.
Difficulty: Medium
Raymond - 014 Chemical... #64
41.
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.
High pressure, low temperature, use of a catalyst. Pressure is kept high because high pressure concentrates the reactants to
a greater extent than it does the products. Temperature is kept low because the reaction is exothermic, and use of a catalyst
facilitates the reaction progress.
Difficulty: Medium
Raymond - 014 Chemical... #81
42.
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?
Kc here will be [Ag+(aq)][Cl-(aq)]. If Keq is very small, then the concentrations of the dissolved ions must also be small,
implying that AgCl is not very soluble.
Difficulty: Medium
Raymond - 014 Chemical... #82
Chapter 14 Review Summary
Category
Difficulty: Difficult
Difficulty: Easy
Difficulty: Medium
Raymond - 014 Chemical...
# of Questions
1
2
39
42