HOMEWORK FOR TEST #2
CHAPTER15: 15.13; 16; 23; 37; 43; 51; 61; 67; 77; 78; 81; 82
CHAPTER16: 16.15; 17; 18; 19; 25; 26; 41; 43; 45; 49; 51; 53; 57; 59; 69; 71; 95; 114
5. A 15.00-L vessel at 700 K initially contains HI(g) at a pressure of 4.00 atm; at equilibrium, it is found
that the partial pressure of H2(g) is 0.387 atm. What is the partial pressure of HI(g) at equilibrium?
2HI(g)
H2(g) + I2(g)
A) 4.00 atm
B) 3.61 atm
C) 3.23 atm
D) 4.39 atm
E) 0.387 atm
ANS: C
6.Sulfur dioxide combines with O2 in the presence of a catalyst as represented by the equation
2SO2(g) + O2(g)
2SO3(g)
Suppose 0.10 mol of SO2 and 0.10 mol of O2 are added to a 1-L vessel. At equilibrium, which of the
following conditions must be true?
A) [O2] = 2[SO3]
B) [SO2] = [O2]
C) [SO2] > [O2]
D) [SO2] < [O2]
E) [SO2] = [O2] = [SO3]
ANS:
D
7.The Ostwald process converts ammonia (NH3) to nitric oxide (NO) by reaction with oxygen in the
presence of a catalyst at high temperatures. In a test of the process a reaction vessel is initially charged
with 3.90 mol NH3(g) and 4.90 mol O2(g), sealed, and heated at a fixed high temperature. When
equilibrium is established the reaction mixture is analyzed and found to contain 2.90 mol NO(g). What is
the quantity of NH3(g) in the equilibrium reaction mixture?
4NH3(g) + 5O2(g)
4NO(g) + 6H2O(g)
A) 1.00 mol NH3(g)
B) 6.80 mol NH3(g)
C) 3.90 mol NH3(g)
D) 1.28 mol NH3(g)
E) 2.00 mol NH3(g)
ANS: A
9.Apply the law of mass action to obtain the equilibrium-constant expression for the following reaction:
2X(g) + Y(g)
3W(g) + V(g)
A) [X]2[Y][W]3[V]
B)
C)
D)
ANS:
B
11.What is the expression for Kc for the following equilibrium?
CaCO3(s)
CaO(s) + CO2(g)
A)
B)
C)
D)
E)
ANS:
B
12.The reaction of a mixture of SO2 and O2 at a given temperature is represented by the equation
2SO2(g) + O2(g)
2SO3(g)
When equilibrium is established, which of the following ratios is constant regardless of the initial
concentrations of SO2 and O2?
A)
B)
C)
D)
E)
ANS:
C
13.What is the balanced equation for the following equilibrium expression?
A)
B)
C)
D)
E)
6SO2(g) + 3O2(g)
6SO3(g)
6SO3(g)
6SO2(g) + 3O2(g)
6SO3(aq)
6SO2(aq) + 3O2(aq)
6SO2(aq) + 3O2(aq)
6SO3(aq)
SO2(g) + O2(g)
ANS:
SO3(g)
A
14.What balanced equation is the following equilibrium expression derived from?
1
2
H (g) + I2(g)
HI(g)
3 2
3
3
B) 2
1
1
HI(g)
H2(g) + I2(g)
3
3
3
C) 1
1
2
H2(aq) + I2(aq)
HI(aq)
3
3
3
D) 2
1
1
HI(aq)
H2(aq) + I2(aq)
3
3
3
A) 1
E) 2HI(g)
ANS: A
H2(g) + I2(g)
15.Which of the following correctly describes the equilibrium constant for the gas-phase reaction between
H2 and O2 to form gaseous H2O?
A)
Kc =
B)
Kc =
C) Kc = [H2O]
D)
Kc =
E)
Kc =
ANS:
D
19.A sample of ammonia gas was allowed to come to equilibrium at 400 K.
2NH3(g)
N2(g) + 3H2(g)
At equilibrium, it was found that the concentration of H2 was 0.0591 M, the concentration of N2 was
0.0197 M, and the concentration of NH3 was 0.441 M. What is Kc for this equilibrium?
A) 3.97  10–3
B) 1.58  10–5
C) 2.10  10–5
D) 2.24  10–1
E) 2.65  10–3
ANS: C
22.A sample of ammonia gas was allowed to come to equilibrium at 400 K.
2NH3(g)
N2(g) + 3H2(g)
At equilibrium, it was found that the concentration of H2 was 0.0367 M, the concentration of N2 was
0.0122 M, and the concentration of NH3 was 0.170 M. What was the initial concentration of ammonia?
A) 0.122 M
B) 0.146 M
C) 0.218 M
D) 0.182 M
E) 0.194 M
ANS: E
23.A sample of ammonia gas was allowed to come to equilibrium at 400 K.
2NH3(g)
N2(g) + 3H2(g)
At equilibrium, it was found that the concentration of H2 was 0.0283 M, the concentration of N2 was
0.00944 M, and the concentration of NH3 was 0.101 M. What is Kp for this equilibrium? (R = 0.0821 L ·
atm/(K · mol))
A) 4.28
B) 2.85
C) 1.70  10–2
D) 1.95  10–8
E) 2.26  10–2
ANS: E
24.For which of the following reactions are the numerical values of Kp and Kc the same?
1. 2SO2(g) + O2(g)
2. N2(g) + O2(g)
3. H2(g) + I2(g)
2SO3(g)
2NO(g)
2HI(g)
A) 1 only
B) 2 only
C) 1 and 2
D) 2 and 3
E) 1, 2, and 3
ANS: D
25.For the reaction 2NO(g) + O2(g)
Kp?
A) Kc = Kp
B) Kc = Kp  (RT)–1
C) Kc = Kp = 1.0
D) Kc = Kp  (RT)¾
2NO2(g) at 750°C, what is the relationship between Kc and
E) Kc = Kp  (RT)1
ANS: E
26.
For which of the following equilibria does Kc = Kp?
A) N2(g) + 3H2(g)
2NH3(g)
B) CO(g) + H2O(g)
CO2(g) + H2(g)
C) CO(g) + 3H2(g)
CH4(g) + H2O(g)
D) CaO(s) + CO2(g)
CaCO3(s)
E) HBr(g)
½H2(g) + ½Br2(l)
ANS: B
27.If Kc = 0.145 for A2 + 2B
4AB
2AB, what is the value of Kc for the reaction
2A2 + 4B?
A) 0.145
B) 0.290
C) 47.6
D) –0.145
E) 3.45
ANS: C
30.At 298 K, the value of Kc for the reaction H2(g) + Br2(g)
HBr(g)
½H2(g) + ½Br2(g)?
2HBr(g) is 2.0  1019. What is Kc for
A) 4.0  10–38
B) 5.0  10–20
C) 1.0  1019
D) –2.0  1019
E) 2.2  10–10
ANS: E
31.Given the equilibrium constants for the following reactions:
4Cu(s) + O2(g)
2CuO(s)
2Cu2O(s); K1
Cu2O(s) + ½ O2(g); K2
What is K for the system
A) (K2)2/(K1)
B) K1  K2
C) (K1)(K2)½
D) (K2)½/(K1)
E) (K1)½/(K2)
ANS: D
2Cu(s) + O2(g)
2CuO(s) equivalent to?
34.What is the Kp equilibrium-constant expression for the following equilibrium?
Ti(s) + 2Cl2(g)
TiCl4(l)
A)
B)
C)
D)
E)
ANS:
A
35.What is the Kc equilibrium-constant expression for the following equilibrium?
S8(s) + 24F2(g)
8SF6(g)
A)
B)
C)
D)
E)
ANS:
E
48.Consider the following equilibrium:
C2H6(g) + C5H12(g)
CH4(g) + C6H14(g); Kp = 9.57 at 500 K
Suppose 47.2 g each of CH4, C2H6, C5H12, and C6H14 are placed in a 25.0-L reaction vessel at 500 K.
Which of the following statements is correct?
A) Because Qc < Kc, more products will be formed.
B) Because Qc = 1, the system is at equilibrium.
C) Because Qc = 1, more products will be formed.
D) Because Qc = 1, more reactants will be formed.
E) Because Qc > Kc, more reactants will be formed.
ANS: A
68.At 550 K, Kp = 7.7  102 for the following equilibrium.
SO2(g) + NO2(g)
SO3(g) + NO(g)
If 0.496 mol each of SO3 and NO are placed in a 5.00-L container at 550 K, what is the concentration of
SO3 at equilibrium? (R = 0.0821 L · atm/(K · mol))
A) 4.3 M
B) 0.096 M
C) 0.099 M
D) 17 M
E) 0.025 M
ANS: B
81.Which of the following equilibria would be affected by volume changes at constant temperature?
1. 2NO(g) + 3F2(g)
2F3NO(g)
2. PCl3(g) + Cl2(g)
PCl5(g)
3. O3(g) + NO(g)
NO2(g) + O2(g)
A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1, 2, and 3
ANS: D