Quiz/Review – Ch 11
1) How many milliliters of 13.0 M H2SO4 are needed to prepare 600.0 mL of 0.10 M H2SO4?
0.22 mL
5.6 mL
2.3 mL
78 mL
4.6 mL
2) A solution containing 299.0 g of Mg(NO3)2 per liter has a density of 1.114 g/mL. The
molarity of the solution is:
2.016 M
2.246 M
1.809 M
6.047 M
None of these choices are correct.
3) What volume of a 0.400 M solution of CaCl2 contains 1.28 g of solute?
4.61 mL
3.20 mL
34.7 mL
71.2 mL
28.8 mL
4) What is the mole percent of ethanol (C2H5OH), which consists of 71.0 g of ethanol for every
19.0 g of water present?
59.4%
1.46%
40.6%
78.9%
8.11%
5) Find the mass percent of CaCl2 in a solution whose molarity is 2.30 M and whose density is
1.19 g/mL.
27.3%
21.4%
25.5%
78.6%
None of these choices are correct.
6) What partial pressure of nitrogen monoxide gas is required in order for 0.00100 g of the gas
to dissolve in 16.0 mL of pure water? The Henry's law constant for nitrogen monoxide gas is
1.9 × 10-3 M atm–1.
6.3 × 10-8 atm
1.2 × 10-7 atm
5.7 × 10-2 atm
1.1 × 100 atm
9.1 × 10-1 atm
7) An ideal solution is formed from a mixture of the nonvolatile solute urea, CO(NH2)2, and
methanol, CH3OH. The vapor pressure of pure methanol at 20°C is 89 mmHg. If 4.0 g of
urea is mixed with 39.5 g of methanol, calculate the vapor pressure of the methanol solution.
14 mmHg
84 mmHg
75 mmHg
81 mmHg
4.6 mmHg
8) At 40°C, heptane has a vapor pressure of about 92.5 torr and octane has a vapor pressure of
about 31.2 torr. Assuming ideal behavior, what is the vapor pressure of a solution that
contains twice as many moles of heptane as octane?
A.51.6 torr
B.72.1 torr
C.61.7 torr
D.82.5 torr
E.None of these choices are correct.
9) Determine the mass of a nonvolatile, nonionizing compound that must be added to 3.00 kg of
water to lower the freezing point to 98.70°C. The molar mass of the compound is 50.0 g/mol
and the Kf for water is 1.86°C kg/mol.
23.8 g
11.6 g
363 g
105 g
159 g
10) Calculate the molarity of a solution containing KCl and water whose osmotic pressure at
22.0°C is 125 torr. Assume complete dissociation of the salt.
0.00679 M
5.16 M
0.0456 M
0.00340 M
0.0911
11) What type of colloid is formed when a gas is dispersed in a liquid?
aerosol
gel
emulsion
foam
sol
Ch-12 Quiz/Review
1) The reaction 2A + 5B → products is first order in A and third order in B. What is the rate law
for this reaction?
rate = k[A]5[B]2
rate = k[A]1[B]3
rate = k[A]3[B]1
rate = k[A]2[B]5
rate = k[A]2/7[B]5/7
2. A first-order reaction is 45% complete at the end of 43 minutes. What is the length of the half-life of
this reaction?
A) 50. min
B) 37 min
C) 2.7 h
D) 62 min
E) none of these
ANS: A
3. The reaction
is first order in N2O5. For this reaction at 45oC, the rate constant k = 1.0  10–5 s–1, where the rate
law is defined as
For a particular experiment ([N2O5]0 = 1.0  10–3 M), calculate [N2O5] after 3.5  105 seconds.
A) 3.5 M
B) 1.0  10–3 M
C) 3.0  10–5 M
D) 0 M
E) 10 M
ANS: C
4. The reaction
is second order in A. When [A]0 = 0.100 M, the reaction is 20.0% complete in 35.9 minutes.
Calculate the value of the rate constant (in L/min·mol).
A)
B)
C)
D)
E)
6.96  10–2
5.57  10–4
1.57
1.11
none of these
ANS: A
5. A particular first-order reaction has a rate constant of 0.0107 s–1. What is the half-life for this reaction?
A) 1.00 s
B) 64.6 s
C) 93.2 s
D) 0.0155 s
E) 0.0107 s
ANS:
B
6. The reaction A  products is second order. If the initial concentration of A is 0.436 M and, after
52.8 seconds have elapsed, the concentration of A has fallen to 0.0476 M, what is the rate
constant of the reaction?
A) 0.0419 M–1 s–1
B) 0.354 M–1 s–1
C) 0.0131 M–1 s–1
D) 0.00736 M–1 s–1
E) 0.0189 M–1 s–1
ANS:
B
7. Consider the reaction, 3 A + 5 B → 4 C + 7 D. If C is being produced at a rate of 2.43 mol/L s, at
what rate is [A] decreasing?
A) 1.82 mol/L s
B) 3.24 mol/L s
C) 3.6 mol/L s
D) –1.82 mol/L s
E) 2.43 mol/L s
ANS: A
8. The decomposition of ozone may occur through the two-step mechanism shown:
The oxygen atom is considered to be a(n)
A) reactant
B) product
C) catalyst
D) reaction intermediate
E) activated complex
ANS: D
9. For the elementary reaction NO3 + CO  NO2 + CO2
a.
b.
c.
d.
the molecularity is 2 and rate = k[NO3][CO]/[NO2][CO2]
the molecularity is 4 and rate = k[NO3][CO]/[NO3][CO]
the molecularity is 4 and rate = k[NO3][CO][NO2][CO2]
the molecularity is 2 and rate = k[NO3][CO]
ANS: D
10. The questions below refer to the following diagram:
Potential Energy
Y
X
A
W
B
C
Z
Reaction Process
Why is this reaction considered to be exothermic?
A) Because energy difference B is greater than energy difference C.
B) Because energy difference B is greater than energy difference A.
C) Because energy difference A is greater than energy difference C.
D) Because energy difference B is greater than energy difference C plus energy
difference A.
E) Because energy difference A and energy difference C are about equal.
ANS: B
11. Use the potential energy diagram shown to answer the following:
a
e
b
c
d
Which letter shows the activation energy (without use of a catalyst)?
A) a
B) b
C) c
D) d
E) e
ANS: A
12. The reaction 3A + 4B  products is second order in A and second order in B. What is the overall
order of the reaction?
A) 0
B) 7
C) 2
D) 4
E) 6
ANS:D
Ch-13 Quiz/Review
1. Which of the following is true about a system at equilibrium?
The concentration(s) of the reactant(s) is equal to the concentration(s) of the product(s).
No new product molecules are formed.
The concentration(s) of reactant(s) is constant over time.
The rate of the reverse reaction is equal to the rate of the forward reaction and both rates are equal to
zero.
None of these choices (A-D) is true.
2. Equilibrium is reached in chemical reactions when:
the concentrations of reactants and products become equal.
all chemical reactions stop.
the rates of the forward and reverse reactions become equal.
the temperature shows a sharp rise.
the forward reaction stops.
3) For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00-L
container.
At equilibrium, the concentration of A is 0.200 mol/L. What is the concentration of B at equilibrium?
0.500 mol/L
0.233 mol/L
0.400 mol/L
0.200 mol/L
None of these choices are correct.
4) If the equilibrium constant for A + B
2C
2A + 2B is:
A.82.6
C is 0.110, then the equilibrium constant for
B.0.780
C.9.09
D.0.220
E.0.110
5. For the equilibrium system:
CO2(g) + H2(g)
CO(g) + H2O(g)
H = +42 kJ/mol
K equals 1.6 at 1260 K. If 0.15 mol each of CO2, H2, CO, and H2O (all at 1260 K) were placed in a
1.0-L thermally insulated vessel that was also at 1260 K, then as the system came to equilibrium:
The temperature would increase and the mass of CO would increase.
The temperature would remain constant and the mass of CO would increase.
The temperature would decrease and the mass of CO would increase.
The temperature would decrease and the mass of CO would decrease.
The temperature would increase and the mass of CO would decrease
6. A mixture of nitrogen and hydrogen was allowed to come to equilibrium at a given temperature.
3H2 + N2
2NH3
An analysis of the mixture at equilibrium revealed 1.8 mol N2, 2.7 mol H2, and 2.7 mol NH3. How
many moles of H2 were present at the beginning of the reaction?
2.7
4.5
6.8
4.1
5.4
7. Exactly 1.0 mol N2O4 is placed in an empty 1.0-L container and is allowed to reach equilibrium
described by the equation N2O4(g)
2NO2(g)
If at equilibrium the N2O4 is 27% dissociated, what is the value of the equilibrium constant, Kc, for
the reaction under these conditions?
0.40
0.74
0.29
0.100
2.5
(083).Which of the following statements concerning equilibrium is not true?
The value of the equilibrium constant for a given reaction mixture is the same regardless of the
direction from which equilibrium is attained.
A system moves spontaneously toward a state of equilibrium.
The equilibrium constant is independent of temperature.
Equilibrium in molecular systems is dynamic, with two opposing processes balancing one another.
A system that is disturbed from an equilibrium condition responds in a manner to restore
equilibrium.
9.Consider the following system at equilibrium: N2(g) + 3H2(g)
2NH3(g) + 92.94 kJ
Which of the following changes will shift the equilibrium to the right?
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
increasing the temperature
decreasing the temperature
increasing the volume
decreasing the volume
removing some NH3
adding some NH3
removing some N2
adding some N2
I, VI, VIII
I, III, V, VII
II, III, V, VIII
I, IV, VI, VII
II, IV, V, VIII
10 (077)Ammonia is prepared industrially by the reaction: N2(g) + 3H2(g)
2NH3(g) for the
reaction: ΔH° = –92.2 kJ and K (at 25°C) = 4.0 × 108. When the temperature of the reaction is
increased to 500°C, which of the following is true?
K for the reaction will be larger at 500°C than at 25°C.
At equilibrium, more NH3 is present at 500°C than at 25°C.
Product formation (at equilibrium) is not favored as the temperature is raised.
The reaction of N2 with H2 to form ammonia is endothermic.
None of these choices is true.
013. Which expression correctly describes the equilibrium constant for the following reaction?
4NH3(g) + 5O2(g)
4NO(g) + 6H2O(g)
K = ( [NO][H2O] ) / ( [NH3][O2] )
K = ( [NO]4[H2O]6 ) / ( [[NH3]4[O2]5 )
K = ( 4[NO] + 6[H2O] ) / (4NH3] + 5[O2] )
K = ( 4NH3] + 5[O2] ) / ( 4[NO] + 6[H2O] )
K = ( [NH3]4[O2]5 ) / ( [NO]4[H2O]6 )
(016) Determine the equilibrium constant for the system N2O4
2NO2 at 25°C. The
concentrations are shown here: [N2O4] = 2.00 × 10–2 M, [NO2] = 1.41 × 10–2 M.
0.497
1.42
9.94 × 10–3
1.01 × 102
0.705
(017)If K = 0.121 for A2 + 2B
2AB, then for 4AB
2A2 + 4B, K would equal:
–0.121
68.3
0.242
0.121
4.13
(024)Consider the following reaction: CS2(g) + 4H2(g)
CH4(g) + 2H2S(g). The equilibrium
constant K is about 0.25 at 900.°C. What is Kp at this temperature?
2.4 × 101
2.3 × 103
2.6 × 10–3
2.7 × 10–5
1.1 × 10–3
(038) For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00-L
container.
A(g) + 2B(g)
C(g)
At equilibrium, the concentration of A is 0.210 mol/L. What is the value of K?
2.32
0.210
9.15
0.587
1.92
(045)A mixture of nitrogen and hydrogen was allowed to come to equilibrium at a given temperature.
3H2 + N2
2NH3
An analysis of the mixture at equilibrium revealed 1.8 mol N2, 2.7 mol H2, and 1.7 mol NH3. How
many moles of H2 were present at the beginning of the reaction?
5.3
4.1
2.7
3.8
4.4
(027)Consider the reaction:
CaCl2(s) + 2H2O(g)
CaCl2·2H2O(s)
The equilibrium constant for the reaction as written is:
K = [H2O]2
K=
K=