Download CHEM 1412. Chapter 15. Chemical Equilibrium (Homework)

CHEM 1412. Chapter 15. Chemical Equilibrium
(Homework) Ky35
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)
+ 5F2 (g) is
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)
3.
of
A.
B.
C.
D.
E.
Br2 (g)
A reaction with an equilibrium constant Kc = 1.5 x 10-25 would consist of which
the following at equilibrium:
approximately equal reactants and products
some reactants and products with reactants slightly favored
some reactants and products with products slightly favored
essentially all reactants
essentially all products
4. The solubility of silver chloride can be increased by dissolving it in a
solution containing ammonia.
AgCl (s)
Ag+ (aq) + Cl- (aq) K1 = 1.6 x 10-10
+
Ag (aq) + 2NH3 (aq)
Ag(NH3)2+ (aq) K2 = 1.5 x 107
What is the value of the equilibrium constant for the overall reaction?
AgCl (s) + 2NH3 (aq)
Ag(NH3)2+ (aq) + Cl- (aq) Knet = ?
7
A. 1.5 x 10
B. 2.4 x 10-3
C. 3.1 x 10-3
D. 2.3 x 1014
E. 2.4 x 107
pg. 1
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
5. When the following reaction is at equilibrium, which of these relationships
is always true?
2 O3(g)
3 O2(g)
A. [O3] = [O2]
B. [O3]2 = [O2]3
C. Kc[O3]2 = [O2]3
D. Kc[O2]3 = [O3]2
E. Kc[O2]2 = [O3]3
6. Calculate Kp for the reaction 2NOCl(g)
400°C for this reaction is 2.1 × 10-2.
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
7. 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
8. Kp for the reaction 4CuO(s)
Kc at this temperature
A. 5.8 x 10-3
B. 41
C. 52
D. 4.6 x 10-3
E. 0.49
2Cu2O(s) + O2(g) is 0.49 at 1024 °C. Calculate
9. 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)
2SO3(g).)
A. 3 × 1024
B. 5 × 1021
C. 2 × 1020
D. 5 × 1022
E. 7 × 1025
pg. 2
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
10. 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
11. 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
B. 3.5 M
C. 4.5 M
D. 7.1 M
E. None of these.
12. At 35ºC, the equilibrium constant for the reaction 2NOCl(g)
2NO(g) +
-5
Cl2(g) is 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
B. 1.0 × 10-2 M
C. 2.8 × 10-1 M
D. 2.4 × 10-2 M
E. 1.6 × 10-3 M
13. 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
B. 0.11 mol/L
C. 0.95 mol/L
D. 2.22 mol/L
E. 18 mol/L
pg. 3
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
14. 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
15. 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
B. 0.138 M
C. 0.0275 M
D. 0.0550 M
E. 0.220 M
16. 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
B. 1.2 M
C. 2.4 M
D. 4.8 M
E. 5.8 M
17. 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
pg. 4
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
18. At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium
6
constant Kc = 4.3 × 10 , and the following concentrations are present: [SO2]
= 0.10 M; [SO3] = 10. M; [O2] = 0.10 M. Which of the following is true based on
the above?
A. Qc > Kc, the reaction proceeds from left to right to reach equilibrium
B. Qc > Kc, the reaction proceeds from right to left to reach equilibrium
C. Qc < Kc, the reaction proceeds from left to right to reach equilibrium
D. Qc < Kc, the reaction proceeds from right to left to reach equilibrium
E. Qc = Kc, the reaction is currently at equilibrium
19. 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 [PCl3] = 0.10
M, [Cl2] = 0.15 M, and [PCl5] = 0.60 M. Which of the following is true based on
the above?
A. Qc > Kc, the reaction proceeds from left to right to reach equilibrium
B. Qc > Kc, the reaction proceeds from right to left to reach equilibrium
C. Qc < Kc, the reaction proceeds from left to right to reach equilibrium
D. Qc < Kc, the reaction proceeds from right to left to reach equilibrium
E. Qc = Kc, the reaction is currently at equilibrium
20.
For the reaction at equilibrium 2SO3
would:
A. Shift
constant
B. Shift
constant
C. Shift
constant
D. Shift
constant
E. Cause
the equilibrium
K
the equilibrium
K
the equilibrium
K
the equilibrium
K
no change
2SO2 + O2 (∆Hºrxn= 198 kJ/mol), increasing the reaction temperature
to the right and increase the value of the equilibrium
to the left and increase the value of the equilibrium
to the right and decrease the value of the equilibrium
to the left and decrease the value of the equilibrium
21. Concerning the following reaction at equilibrium:
3Fe(s) + 4H2O(g)
Fe3O4(s) + 4H2(g), increasing the concentration of the Fe(s)
would:
A. Shift the equilibrium to the right
B. Shift the equilibrium to the left
C. Increase the value of the equilibrium constant, K
D. Decrease the value of the equilibrium constant, K
E. Cause no change
pg. 5
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
22. 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.
23.
The common allotropes of carbon (graphite and diamond) equilibrate as follows: C(gr)
C(dia) with
equilibrium constant K = 0.32. The molar volumes of graphite and diamond are, respectively, 5.30 cm3/mol
3
and 3.42 cm /mol; ∆Hf of diamond is 1.90 kJ/mol. This data suggests that the formation of diamond is favored
at
A.
B.
C.
D.
low temperatures and low pressures.
high temperatures and low pressures.
low temperatures and high pressures.
high temperatures and high pressures.
24.
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.
25.
Consider this 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.
B.
C.
D.
A shift to produce more SO2
A shift to produce more O2
No change
A shift to produce more SO3
pg. 6
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
26. For the reaction 2NOCl(g)
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
B. 2.25 M
C. 2.50 M
D. 3.52 M
E. 11.0 M
27.
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)
H2O(g) + Cu(s) ∆Hºrxn = -2.0 kJ/mol
A.
B.
C.
D.
E.
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.
28.
Which of the following rate laws is consistent with the following mechanism?
A2(g) + C(g)
AC(g) + A(g) fast equilibrium (Kc1)
AC(g) + B2(g) → AB2(g) + C(g) slow
A.
B.
C.
D.
E.
Rate
Rate
Rate
Rate
Rate
=
=
=
=
=
k[A2][C]
k[AB2][C]/[AC][B2]
kKc1[A2][C][B2]/[A]
[A][AB2]/[A2][B2]
kKc1[AC][A]/[A2][C]
29. A solution was prepared such that the initial concentrations of Cu2+(aq) and
CN-(aq) were 0.0120 M and 0.0400 M, respectively. These ions react according
to the following chemical equation:
Cu2+(aq) + 4CN-(aq)
Cu(CN)42--(aq)
Kc = 1.0 × 1025
What will be the concentration of Cu2+(aq) at equilibrium?
A.
B.
C.
D.
E.
0.0020 M
0.0040 M
0.0060 M
0.0080 M
None of the above
pg. 7
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
30. Consider the reaction, N2(g) + 3H2(g)
2NH3(g). Kc = 8.1 x 10-3 at 900 K.
What is the value of Kc for NH3(g)
½N2(g) + 3/2H2(g)?
A. 17
B. 15
C. 13
D. 11
E. None of the above
31. 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.
A. Kc = 15.3
B. Kc = 17.3
C. Kc = 19.3
D. Kc = 21.3
E. None of the above
32. 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).
A. 10 M
B. 20 M
C. 30 M
D. 40 M
E. None of the above
33. 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.
A. 210
B. 230
C. 250
D. 270
E. None of the above
pg. 8
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
34. 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.
A. 1.2 mol
B. 1.4 mol
C. 1.6 mol
D. 1.8 mol
E. None of the above
35.
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.
A.
B.
C.
D.
E.
1.2 mol
1.4 mol
1.6 mol
1.8 mol
None of the above
pg. 9
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
CHEM 1412. Chapter 15. Chemical Equilibrium
(Homework) Ky35 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]
2. The equilibrium constant expression for the reaction 2BrF5 (g)
+ 5F2 (g) is
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)
3.
of
A.
B.
C.
D.
E.
Br2 (g)
A reaction with an equilibrium constant Kc = 1.5 x 10-25 would consist of which
the following at equilibrium:
approximately equal reactants and products
some reactants and products with reactants slightly favored
some reactants and products with products slightly favored
essentially all reactants
essentially all products
pg. 1
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
4. The solubility of silver chloride can be increased by dissolving it in a
solution containing ammonia.
AgCl (s)
Ag+ (aq) + Cl- (aq) K1 = 1.6 x 10-10
+
Ag (aq) + 2NH3 (aq)
Ag(NH3)2+ (aq) K2 = 1.5 x 107
What is the value of the equilibrium constant for the overall reaction?
AgCl (s) + 2NH3 (aq)
Ag(NH3)2+ (aq) + Cl- (aq) Knet = ?
7
A. 1.5 x 10
B. 2.4 x 10-3
C. 3.1 x 10-3
D. 2.3 x 1014
E. 2.4 x 107
5. When the following reaction is at equilibrium, which of these relationships
is always true?
2 O3(g)
3 O2(g)
A. [O3] = [O2]
B. [O3]2 = [O2]3
C. Kc[O3]2 = [O2]3
D. Kc[O2]3 = [O3]2
E. Kc[O2]2 = [O3]3
6. Calculate Kp for the reaction 2NOCl(g)
400°C for this reaction is 2.1 × 10-2.
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
7. 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
pg. 2
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
8. Kp for the reaction 4CuO(s)
Kc at this temperature
A. 5.8 x 10-3
B. 41
C. 52
D. 4.6 x 10-3
E. 0.49
2Cu2O(s) + O2(g) is 0.49 at 1024 °C. Calculate
9. 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)
2SO3(g).)
A. 3 × 1024
B. 5 × 1021
C. 2 × 1020
D. 5 × 1022
E. 7 × 1025
10. 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
11. 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
B. 3.5 M
C. 4.5 M
D. 7.1 M
E. None of these.
pg. 3
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
12. At 35ºC, the equilibrium constant for the reaction 2NOCl(g)
2NO(g) +
-5
Cl2(g) is 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
B. 1.0 × 10-2 M
C. 2.8 × 10-1 M
D. 2.4 × 10-2 M
E. 1.6 × 10-3 M
13. 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
B. 0.11 mol/L
C. 0.95 mol/L
D. 2.22 mol/L
E. 18 mol/L
14. 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
15. 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
B. 0.138 M
C. 0.0275 M
D. 0.0550 M
E. 0.220 M
pg. 4
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
16. 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
B. 1.2 M
C. 2.4 M
D. 4.8 M
E. 5.8 M
17. 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
18. At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium
6
constant Kc = 4.3 × 10 , and the following concentrations are present: [SO2]
= 0.10 M; [SO3] = 10. M; [O2] = 0.10 M. Which of the following is true based on
the above?
A. Qc > Kc, the reaction proceeds from left to right to reach equilibrium
B. Qc > Kc, the reaction proceeds from right to left to reach equilibrium
C. Qc < Kc, the reaction proceeds from left to right to reach equilibrium
D. Qc < Kc, the reaction proceeds from right to left to reach equilibrium
E. Qc = Kc, the reaction is currently at equilibrium
19. 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 [PCl3] = 0.10
M, [Cl2] = 0.15 M, and [PCl5] = 0.60 M. Which of the following is true based on
the above?
A. Qc > Kc, the reaction proceeds from left to right to reach equilibrium
B. Qc > Kc, the reaction proceeds from right to left to reach equilibrium
C. Qc < Kc, the reaction proceeds from left to right to reach equilibrium
D. Qc < Kc, the reaction proceeds from right to left to reach equilibrium
E. Qc = Kc, the reaction is currently at equilibrium
pg. 5
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
20.
For the reaction at equilibrium 2SO3
would:
A. Shift
constant
B. Shift
constant
C. Shift
constant
D. Shift
constant
E. Cause
the equilibrium
K
the equilibrium
K
the equilibrium
K
the equilibrium
K
no change
2SO2 + O2 (∆Hºrxn= 198 kJ/mol), increasing the reaction temperature
to the right and increase the value of the equilibrium
to the left and increase the value of the equilibrium
to the right and decrease the value of the equilibrium
to the left and decrease the value of the equilibrium
21. Concerning the following reaction at equilibrium:
3Fe(s) + 4H2O(g)
Fe3O4(s) + 4H2(g), increasing the concentration of the Fe(s)
would:
A. Shift the equilibrium to the right
B. Shift the equilibrium to the left
C. Increase the value of the equilibrium constant, K
D. Decrease the value of the equilibrium constant, K
E. Cause no change
22. 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.
pg. 6
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
23.
The common allotropes of carbon (graphite and diamond) equilibrate as follows: C(gr)
C(dia) with
equilibrium constant K = 0.32. The molar volumes of graphite and diamond are, respectively, 5.30 cm3/mol
and 3.42 cm3/mol; ∆Hf of diamond is 1.90 kJ/mol. This data suggests that the formation of diamond is favored
at
A.
B.
C.
D.
low temperatures and low pressures.
high temperatures and low pressures.
low temperatures and high pressures.
high temperatures and high pressures.
24.
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.
25.
Consider this 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.
B.
C.
D.
A shift to produce more SO2
A shift to produce more O2
No change
A shift to produce more SO3
pg. 7
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
26. For the reaction 2NOCl(g)
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
B. 2.25 M
C. 2.50 M
D. 3.52 M
E. 11.0 M
27.
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)
H2O(g) + Cu(s) ∆Hºrxn = -2.0 kJ/mol
A.
B.
C.
D.
E.
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.
28.
Which of the following rate laws is consistent with the following mechanism?
A2(g) + C(g)
AC(g) + A(g) fast equilibrium (Kc1)
AC(g) + B2(g) → AB2(g) + C(g) slow
A.
B.
C.
D.
E.
Rate
Rate
Rate
Rate
Rate
=
=
=
=
=
k[A2][C]
k[AB2][C]/[AC][B2]
kKc1[A2][C][B2]/[A]
[A][AB2]/[A2][B2]
kKc1[AC][A]/[A2][C]
29. A solution was prepared such that the initial concentrations of Cu2+(aq) and
CN-(aq) were 0.0120 M and 0.0400 M, respectively. These ions react according
to the following chemical equation:
Cu2+(aq) + 4CN-(aq)
Cu(CN)42--(aq)
Kc = 1.0 × 1025
What will be the concentration of Cu2+(aq) at equilibrium?
A.
B.
C.
D.
E.
0.0020 M
0.0040 M
0.0060 M
0.0080 M
None of the above
pg. 8
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
30. Consider the reaction, N2(g) + 3H2(g)
2NH3(g). Kc = 8.1 x 10-3 at 900 K.
What is the value of Kc for NH3(g)
½N2(g) + 3/2H2(g)?
A. 17
B. 15
C. 13
D. 11
E. None of the above
31. 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.
A. Kc = 15.3
B. Kc = 17.3
C. Kc = 19.3
D. Kc = 21.3
E. None of the above
32. 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).
A. 10 M
B. 20 M
C. 30 M
D. 40 M
E. None of the above
33. 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.
A. 210
B. 230
C. 250
D. 270
E. None of the above
pg. 9
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
34. 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.
A. 1.2 mol
B. 1.4 mol
C. 1.6 mol
D. 1.8 mol
E. None of the above
35.
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.
A.
B.
C.
D.
E.
1.2 mol
1.4 mol
1.6 mol
1.8 mol
None of the above
pg. 10
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35
pg. 1
CHEM 1412. Chapter 15. Chemical Equilibrium (Homework) Ky35