NAME:
PERIOD:
CHAPTER 13 REVIEW PROBLEMS
(70 points)
(2 points each) 1. Write the equilibrium expression for each of the following reactions and state whether the
reaction is homogeneous or heterogeneous.
a.
3 NO (g) ↔ N2O (g) + NO2 (g)
b.
Ni(CO4) (g) ↔ Ni (s) + 4 CO (g)
c.
CH4 (g) + 2 H2S (g) ↔ CS2 (g) + 4 H2 (g)
d.
2 Ag (s) + Zn2+ (aq) ↔ 2 Ag+ (aq) + Zn (s)
(2 points each) 2. When the following reactions come to equilibrium, does the equilibrium mixture contain mostly
reactants or mostly products?
a.
N2 (g) + O2 (g) ↔ 2 NO (g)
K = 1.5 x 10-10
b.
2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)
K = 2.5 x 109
(2 points each) 3. At 1000K, Kp = 1.85 for the reaction
SO2 (g) + ½ O2 (g) ↔ SO3 (g)
a.
Calculate the value of Kp for the reaction: SO3 (g) ↔ SO2 (g) + ½ O2 (g)
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b.
Calculate the value of Kp for the reaction: 2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)
c.
Calculate the value of K for the reaction in part (b).
(2 points each) 4. Mercury (I) oxide decomposes into elemental mercury and elemental oxygen:
2 Hg2O (s) ↔ 4 Hg (l) + O2 (g)
a.
Write the equilibrium constant expression for this reaction in terms of partial pressures.
b.
Explain why we normally exclude pure solids and liquids from the equilibrium constant expression.
(4 points) 5. Gaseous hydrogen iodide is placed in a closed container at 4250C, where it partially decomposes to
hydrogen and iodide:
2 HI (g) ↔ H2 (g) + I2 (g)
At equilibrium it is found that [HI] = 3.53 x 10 -3 M, [H2] = 4.79 x 10-4 M and [I2] = 4.79 x 10-4 M. Calculate the
value of K at that temperature.
(4 points) 6. The equilibrium for 2 NO (g) + Cl2 ↔ 2 NOCl (g) is established at 500.0K. An equilibrium mixture
of the gases has partial pressures of 0.0950 atm for NO, 0.171 atm for Cl 2 , and 0.280 atm for NOCl. Calculate the
Kp for this reaction.
(2 points each) 7.
a.
How does the reaction quotient differ from the equilibrium constant?
b.
If Q < K, in which direction will a reaction proceed in order to reach equilibrium?
c.
What condition must be satisfied so Q = K?
(3 points each) 8. At 1000C the equilibrium constant for the reaction COCl2 (g) ↔ CO (g) + Cl2 (g) has a value of
K = 2.19 x 10-10. Indicate whether each of the following mixtures of COCl 2, Co, and Cl2 are at equilibrium. If not,
which direction must the reaction shift in order to achieve equilibrium?
a.
[COCl2] = 2.00 x 10-3 M, [CO] = 3.30 x 10-6 M, [Cl2] = 6.62 x 10-1 M
b.
[COCl2] = 4.50 x 10-2 M, [CO] = 1.10 x 10-7 M, [Cl2] = 2.25 x 10-6 M
c.
[COCl2] = 0.0100 M, [CO] = [Cl2] = 1.48 x 10-6 M
(3 points) 9. At 1000C, K = 0.078 for the reaction
SO2Cl2 (g) ↔ SO2 (g) + Cl2
In an equilibrium mixture of the three gases, the concentrations of SO 2Cl2 = 0.108 M and SO2 = 0.052 M. Calculate
the equilibrium concentration of Cl2.
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(3 points) 10. At 1200 K, K = 3.92 for the reaction
CO (g) + 3 H2 (g)  CH4 (g) + H2O (g)
In an equilibrium mixture of the gases, [CO] = 0.30 M, [H2] = 0.10 M and [H2O] = 0.02 M. Calculate the
equilibrium concentration of CH4.
(3 points) 11. At 900 K the following reaction has a Kp = 0.345
2 SO2 (g) + O2 (g)  2 SO3 (g)
In an equilibrium mixture, the partial pressures of SO2 and O2 are 0.165 atm and 0.755 atm, respectively. Calculate
the partial pressure of the SO3.
(5 points) 12. The reaction
CO (g) + H2O (g)  CO2 (g) + H2 (g)
is used to increase the ratio of hydrogen in synthesis gas (mixtures of CO and H2). Suppose you start with 1.00 mole
each of carbon monoxide and water vapor in a 50.0 L container. Calculate the equilibrium concentration of each
substance. The equilibrium constant, K, is 0.58.
(5 points) 13. Hydrogen and iodine react according to the following equation:
H2 (g) + I2 (g)  2 HI (g)
Suppose 1.00 mole H2 and 2.00 moles I2 are placed in a 1.00 L container. Calculate the concentrations of the
substances when the mixture comes to equilibrium at 458 0C. K = 49.7.
(1 point each) 14. Consider the following equilibrium, for which H , 0:
2 SO2 (g) + O2 (g)  2 SO3 (g)
How will each of the following changes affect an equilibrium mixture of the three gases?
a.
O2 (g) is added to the system.
b.
the reaction mixture is heated.
c.
the volume of the reaction vessel is doubled.
d.
a catalyst is added to the mixture.
e.
the total pressure of the system is increased by adding a noble gas.
f.
SO3 (g) is removed form the system.
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