Unit 6 Practice Questions
I.
Solutions
Questions 1-4 refer to the following:
(A)
(B)
(C)
(D)
(E)
Solute
Solvent
Solubility
Aqueous solution
Solvation
1.
2.
3.
4.
Is present in a lesser amount in a solution
Solvent is water
Is present in greater quantity in a solution
Interaction between the solute and solvent
molecules
1
Questions 1-2 refer to the following:
(A)
(B)
(C)
(D)
(E)
1 molar
1 molal
0.5 molar
0.5 molal
25 molar
1. The concentration of a solution of Ca(OH)2 when 74
grams are completely dissolved in a container holding 2
liters of water?
2. The concentration of a solution of sucrose, C12H22O11,
when 684 grams are completely dissolved in 2,000 grams
of water?
2
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Dilute
Concentrated
Unsaturated
Saturated
Supersaturated
1. The condition, unrelated to quantities, that indicates that the
rate going into solution is equal to the rate coming out of the
solution
2. The condition that exists when a water solution that has been
at equilibrium and saturated is heated to a higher
temperature with a higher solubility, but no additional solute
is added
3. The descriptive term that indicates there is a large quantity of
solute, compared with the amount of solvent, in a solution
3
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Nitrogen dioxide, NO2(g)
Iodine, I2(s)
Glucose, C6H12O6(s)
Naphthalene, C10H8(s)
Calcium oxide, CaO(s)
1. Yields an electrolyte solution upon dissolution in water
2. Solubility in water increases as temperature is decreased
3. Produces the greatest boiling point elevation per mole
dissolved into 1 L of water
4
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Molarity
Molality
Mole fraction
Density
Partial pressure
1. Is measured in units of atmosphere or millimeters of
mercury
2. Is measured in units of moles/kilogram
3. Is the quantity used in the calculation of boiling point
elevation
5
II
I
A salt dissolved in
an organic solvent
will be a good
electrical
conductor
BECAUSE
Salts will not dissolve
appreciably in an organic
solvent
Salt dissolved in
water depresses
the freezing point
BECAUSE
The solute particles
interfere with ice crystal
formation
6
II
I
A saturated
solution can be
classified as dilute
BECAUSE
A solute can have a very
low solubility in a solvent
Crystals of sodium
chloride go into
solution in water as
ions
BECAUSE
The sodium ion has a 1+
charge and the chloride ion
has a 1- charge and they
are hydrated by the water
molecules
7
II
I
A saturated
solution is not
necessarily
concentrated
BECAUSE
Dilute and concentrated are
terms that relate only to
the relative amount of
solute dissolved in the
solvent
When a crystal is
added to a
supersaturated
solution of itself,
the crystal does not
appear to change
BECAUSE
the supersaturated solution
is holding more solute than
its normal solubility
8
II
I
Freezing point
depression caused
by a 2-molal
aqueous solution of
nonionic solute is
equal to one-half
the freezing point
depression caused
by a 2-molal
aqueous solution of
NaCl
BECAUSE
the supersaturated solution
is holding more solute than
its normal solubility
9
II
I
Aqueous solutions
with ionic solutes
conduct electricity
BECAUSE
a liquid solvent becomes
saturated when the solute
reaches the limit of its
solubility
An ionic solid is a
good conductor of
electricity
BECAUSE
An ionic solid is composed
of positive and negative
ions joined together in a
lattice structure held
together by electrostatic
forces
10
II
I
According to the
equation M1V1 =
M2V2, as the
volume increases
the molarity
decreases
BECAUSE
As water is added to a
solution the solution is
diluted
A 1 m NaCl(aq)
solution will freeze
at a temperature
below 273 K
BECAUSE
As a solute is added to a
solvent, the boiling point
increases while the freezing
point decreases
11
II
I
Gases become
more soluble in
water with an
increase in
temperature
BECAUSE
Heating up water forces the
water molecules closer
together to hold gas
molecules in solution
12
How much NaOH must be added to make 200 mL of a 1 M
NaOH solution?
(A)
(B)
(C)
(D)
8g
16 g
40 g
80 g
13
To what volume must 10.0 mL of 5.00 M HCl be diluted to
make a 0.500 M HCl solution?
(A)
(B)
(C)
(D)
(E)
1 mL
50 mL
100 mL
500 mL
1,000 mL
14
Which of the following will be the most electrically
conductive?
(A)
(B)
(C)
(D)
Sugar dissolved in water
Salt water
Salt dissolved in organic solvent
An oil and water mixture
15
If you mix 3 L of 0.5 M NaCl with 9 L of 0.2777 M NaCl, what
will the concentration of the final solution be, assuming that
volumes are additive?
(A)
(B)
(C)
(D)
(E)
0.33 M
0.39 M
0.5777 M
1.6662 M
None of the above
16
Which of the following statements about boiling-point elevation is
NOT true?
I.
Addition of a nonvolatile solute raises the vapor pressure of a
solution. Therefore, a higher temperature will be needed to
produce boiling.
II. The molal concentration of solute particles dissolved in the
solvent is the important factor in determining the molal
boiling boiling-point elevation constant
III. The identity of solute particles dissolved in the solvent is an
important factor in determining the molal boiling-point
elevation constant.
(A)
(B)
(C)
(D)
(E)
I only
II only
I and III only
II and III only
I, II, and III
17
Which of the following can be classified as a strong
electrolyte?
(A)
(B)
(C)
(D)
(E)
Br2
C6H12O6
CaCl2
H2O
NO3
18
How many grams of potassium chloride, KCl, must be added
to make 500 mL of 1.00 M KCl solution?
(A)
(B)
(C)
(D)
(E)
1.00 g
18.6 g
37.3 g
74.5 g
149 g
19
How many moles of potassium ions are present in 2.50 L of
0.200 M potassium sulfate?
(A)
(B)
(C)
(D)
(E)
0.0800 mol
0.160 mol
0.400 mol
0.500 mol
1.00 mol
20
If 1 mole of each of the following substances was dissolved
in 1,000 grams of water, which solution would have the
highest boiling point?
(A)
(B)
(C)
(D)
(E)
NaCl
KCl
CaCl2
C6H10O5
C12H22O11
21
Two water solutions are made in the laboratory, one of
glucose (molar mass = 180 g/mol), the other of sucrose
(molar mass = 342 g/mol). If the glucose solution had 180
grams in 1,000 grams of water and the sucrose had 342
grams in 1,000 grams of water, which statement about the
following points of the solution is the most accurate?
(A) The glucose solution would have the lower freezing point
(B) The sucrose solution would have the lower freezing point
(C) The freezing point of the sucrose solution would be
lowered twice as much as that of the glucose solution
(D) Both solutions would have the same freezing point
(E) The freezing points of the solutions would not be
affected, because both solutions are nonpolar
22
A solution can be both
(A)
(B)
(C)
(D)
Dilute and concentrated
Saturated and dilute
Saturated and unsaturated
Supersaturated and saturated
23
The solubility of a solute must indicate
(A)
(B)
(C)
(D)
The temperature of the solution
The quantity of solute
The quantity of solvent
All of the above
24
When another crystal was added to a water solution of the
same substance, the crystal seemed to remain unchanged.
Its particles were
(A)
(B)
(C)
(D)
Going into an unsaturated solution
Exchanging places with others in the solution
Causing the solution to become supersaturated
Not going into solution in this static condition
25
A 10.0% solution of NaCl means that in 100. grams of
solution there is
(A)
(B)
(C)
(D)
5.85 g NaCl
58.5 g NaCl
10. g NaCl
94 g H2O
26
The molarity of a solution made by placing 98 grams of
H2SO4 in sufficient water to make 500. milliliters of solution is
(A)
(B)
(C)
(D)
0.5
1
2
3
27
If 684 grams of sucrose (molar mass = 342 g/mol) is
dissolved in 2,000 grams of water (essentially 2 L), what will
be the freezing point of this solution?
(A)
(B)
(C)
(D)
-0.51°C
-1.86°C
-3.72°C
-6.58°C
28
Forty grams of sodium hydroxide is dissolved in enough
water to make 1 liter of solution. What is the molarity of the
solution?
(A)
(B)
(C)
(D)
(E)
0.25 M
0.5 M
1M
1.5 M
4M
29
How much water, in liters, must be added to 0.50 liter of 6.0
M HCl to make the solution 2.0 M?
(A)
(B)
(C)
(D)
(E)
0.33
0.50
1.0
1.5
2.0
30
How many grams of NaOH are needed to make 100 grams of
a 5% solution?
(A)
(B)
(C)
(D)
(E)
2
5
20
40
95
31
If 0.1 mole of K2SO4 was added to the saturated solution of
BaSO4 at 25°C containing 3.9 x 10-5 mole/liter of Ba2+ ions,
what would happen to the Ba2+ concentration?
(A)
(B)
(C)
(D)
(E)
It would increase
It would decrease
It would remain the same
It would first increase, then decrease
It would first decrease, then increase
32
When 1 mole of NaCl is dissolved in 1,000 grams of water,
the boiling point of the water is changed to
(A)
(B)
(C)
(D)
(E)
100.51°C
101.02°C
101.53°C
101.86°C
103.62°C
33
To what volume, in milliliters, must 50.0 milliliters of 3.50 M
H2SO4 be diluted in order to make 2.00 M H2SO4?
(A)
(B)
(C)
(D)
(E)
25.0
60.1
87.5
93.2
101
34
What is the molar mass of a nonionizing solid if 10. grams of
this solid, dissolved in 200. grams of water, formed a solution
that froze at -3.72°C?
(A)
(B)
(C)
(D)
(E)
25. g/mol
50. g/mol
100. g/mol
150. g/mol
1,000. g/mol
35
How many grams of NaCl will be needed to make 100.
milliliters of 2 M solution?
(A)
(B)
(C)
(D)
(E)
5.85
11.7
29.2
58.5
117
36
How many grams of H2SO4 are in 1,000 grams of a 10.%
solution? (1 mol of H2SO4 = 98g)
(A)
(B)
(C)
(D)
(E)
1.0
9.8
10.
98
100.
37
If 1 mole of ethyl alcohol in 1,000 grams of water depresses
the freeing point by 1.86° Celsius, what will be the freezing
point of a solution of 1 mole of ethyl alcohol in 500 grams of
water?
(A)
(B)
(C)
(D)
(E)
-0.93°C
-1.86°C
-2.79°C
-3.72°C
-5.58°C
38
Which of the following will most likely increase the solubility
of NaCl in water?
(A)
(B)
(C)
(D)
(E)
Reducing the temperature of the water
Raising the temperature of the water
Reducing the molality of the solution
Raising the molality of the solution
Raising the molarity of the solution
39
Which of the following would most likely give a sample of
water the capacity to conduct electricity?
(A)
(B)
(C)
(D)
(E)
Reducing the temperature of the water
Raising the temperature of the water
Removing all electrolytes from the water
Dissolving a nonionic substance in the water
Dissolving CaCl2 in the water
40
When 190 grams of MgCl2 are dissolved in water and the
resulting solution is 500 milliliters in volume, what is the
molar concentration of MgCl2 in the solution?
(A)
(B)
(C)
(D)
(E)
2.0 M
4.0 M
8.0 M
12.0 M
16.0 M
41
Which of the following will raise the boiling point of a
sample of water?
(A)
(B)
(C)
(D)
(E)
Heat the water
Mix gasoline into the water
Bring the water sample to a higher altitude
Place the water sample on a magnetic stirrer
Dissolve table sugar into the water
42
The ionic solid Fe(OH)3 is added to water and dissociates into
its component ions, as shown above. The solubility product
expression for the saturated solution is
(A) Ksp = [Fe3+] [OH-]
(B) Ksp = [Fe3+] [3OH-]
(C) Ksp = [Fe3+] [3OH-]3
(D) Ksp = [Fe3+] [OH-]3
(E) Ksp =
Fe3+ OH− 3
[Fe OH 3 ]
43
All of the following when added to water will produce an
electrolyte solution EXCEPT
(A)
(B)
(C)
(D)
(E)
N2 (g)
HCl (g)
KOH (s)
NaI (s)
CaCl2 (s)
44
What is the molar concentration of a 500-milliliter solution
that contains 20 grams of CaBr2 (formula weight = 200)?
(A) 0.1 molar
(B) 0.2 molar
(C) 0.5 molar
(D) 1 molar
(E) 5 molar
45
Based on the solubility products given below, which of the
following salts is the most soluble?
(A)
(B)
(C)
(D)
(E)
BaCO3
PbCrO4
AgCl
CaSO4
ZnC2O4
Ksp = 5.1 x 10-9
Ksp = 2.8 x 10-13
Ksp = 1.8 x 10-10
Ksp = 9.1 x 10-6
Ksp = 2.7 x 10-8
46
Ca3 PO4
2
s ⇌ 3
Ca2+
aq + 2 PO4
3−
(aq)
What is the solubility product expression for the dissolution
of Ca3(PO4)2 where the above is true?
(A)
(B)
(C)
(D)
(E)
Ksp = [Ca2+]3 [PO43-]2
Ksp = [Ca2+]2 [PO43-]3
Ksp = [Ca2+] [PO43-] / [Ca3(PO4)2]
Ksp = [Ca2+]3 [PO43-]2 / [Ca3(PO4)2]
Ksp = [Ca2+]2 [PO43-]3 / [Ca3(PO4)2]
47
117 grams of NaCl are dissolved in water to make 500 mL of
solution. Water is then added to this solution to make a total
of one liter of solution. The final molarity of this solution will
be
(A)
(B)
(C)
(D)
(E)
4M
2M
1M
0.5 M
0.585 M
48
A solution of a salt and 100 grams of water that can still
dissolve more solute at a given temperature is classified as
(A)
(B)
(C)
(D)
(E)
Unsaturated
Supersaturated
Saturated
Anhydrous
Hypertonic
49
Which solution listed below is going to have the highest
boiling point?
(A)
(B)
(C)
(D)
(E)
1.5 m NaCl
1.5 m AgCl
2.0 m C6H12O6
2.0 m CaCl2
1.0 m Al2(SO4)3
50
110 grams of KF are dissolved in water to make 850 mL of
solution. What is the molarity of the solution?
(A)
(B)
(C)
(D)
(E)
0.129 M
0.620 M
0.002 M
0.068 M
2.23 M
51
Which mole sample of the solids below is best for melting a
500-gram sheet of ice on a sidewalk?
(A)
(B)
(C)
(D)
(E)
NaCl
CaCl2
KBr
AgNO3
NaC2H3O2
52
One mole of each of the following substances is dissolved in
1.0 kg of water. Which solution will have the lowest freezing
point?
(A)
(B)
(C)
(D)
(E)
NaC2H3O2
NaCl
MgCl2
CH3OH
C6H12O6
53
Which amount of Pb(NO3)2, when added to enough water to
make 1 liter of solution, will produce a solution with a
molarity of 1.0 M?
(A)
(B)
(C)
(D)
(E)
144 grams
331 grams
317 grams
0.003 moles
0.5 moles
54
Of the substances below, which is best able to conduct
electricity?
(A)
(B)
(C)
(D)
(E)
KBr(l)
NaC2H3O2(s)
C6H12O6(aq)
CH3OH(aq)
NaCl(s)
55
Which of the following statements about solubility is
correct?
(A) Gases decrease in solubility with an increase in
temperature
(B) NaCl is insoluble in water
(C) PbI2 is soluble in water
(D) All nitrates are insoluble in water
(E) Solubility depends solely upon the amount of solvent
used
56
Which aqueous solution has a molarity of 1.0 M?
(A) 73 grams of HCl dissolved to make 2.0 liters of solution
(B) 360 grams of C6H12O6 dissolved to make 1.5 liters of
solution
(C) 94 grams of K2O dissolved to make 0.75 liters of solution
(D) 24 grams of LiOH dissolved to make 1.25 liters of
solution
(E) 40 grams of HF dissolved to make 2.50 liters of solution
57
Which aqueous solution is expected to have the highest
boiling point?
(A)
(B)
(C)
(D)
(E)
1.5 m FeCl2
3.0 m CH3OH
2.5 m C6H12O6
2.5 m NaCl
1.0 m CaCl2
58
II. Equilibrium
II
I
An equation where
two gas molecules
combine to form
one gas molecule in
equilibrium will
increase the yield
of the product
when the pressure
is increased
BECAUSE
Increased pressure always
favors products
59
II
I
A reaction is at
equilibrium when it
reaches completion
BECAUSE
The concentration of the
reactants in a state of
equilibrium equal the
concentrations of the
products
60
II
I
In a reaction that has
both a forward and a
reverse reaction, 𝐴 +
𝐵 ⇌ 𝐴𝐵, when only
A and B are
introduced into a
reacting vessel, the
forward reaction rate
is the highest at the
beginning and begins
to decrease from
that point until
equilibrium is
reached
BECAUSE
The reverse reaction does not
begin until equilibrium is
reached
61
II
I
At equilibrium, the
forward reaction and
the reverse reaction
stop
BECAUSE
At equilibrium, the reactants
and products have reached
the equilibrium
concentrations
Equilibrium is a static
condition
BECAUSE
At equilibrium, the forward
reaction rate equals the
reverse reaction rate
62
II
I
Pressure applied to a
gaseous system in
equilibrium favors
the forward reaction
BECAUSE
The product side of an
equilibrium would show an
increase in gas pressure
If the forward
reaction of an
equilibrium is
exothermic, adding
heat to the system
favors the reverse
reaction
BECAUSE
Additional heat causes a
stress on the system, and the
system moves in the direction
that releases the stress
63
I
II
For any chemical
reaction in dynamic
equilibrium,
increasing the
concentration of one
product will decrease
the concentration of
all reactants
BECAUSE
A dynamic equilibrium will
shift in a direction that tends
to relieve a stress imposed on
it
When a reversible
chemical reaction
reaches equilibrium,
concentrations of
products and
reactants are always
equal
BECAUSE
Additional heat causes a
stress on the system, and the
system moves in the direction
that releases the stress
64
I
II
When the
temperature of a
reaction at
equilibrium is
increased, the
equilibrium will shift
to favor the
endothermic
reaction
BECAUSE
At equilibrium, all reactants
have been converted into
products
At equilibrium the
concentration of
reactants and
products remain
constant
BECAUSE
At equilibrium the rates of the
forward and reverse reactions
are equal
65
If Kc >> 1,
(A) The equilibrium mixture will favor products over
reactants
(B) The equilibrium mixture will favor reactants over
products
(C) The equilibrium amounts of reactants and products are
equal
(D) The reaction is irreversible
66
BaCl2 dissociates in water to give one Ba2+ ion and two Clions. If concentrated HCl is added to this solution:
(A)
(B)
(C)
(D)
(E)
[Ba2+] increases
[Ba2+] remains constant
[OH-] increases
The number of moles of undissociated BaCl2 increases
[H+] decreases
67
Consider the following gas phase reaction:
H2 (g) + Br2 g ⇌ 2HBr(g)
The concentrations of H2, Br2, and HBr are 0.05 M, 0.03 M,
and 500.0 M, respectively. The concentration equilibrium
constant for this reaction at 400°C is 2.5 x 103. Is this system
at equilibrium?
(A) Yes, the system is at equilibrium
(B) No, the reaction must shift to the right in order to reach
equilibrium
(C) No, the reaction must shift to the left in order to reach
equilibrium
(D) It cannot be determined
(E) This system will never be at equilibrium
68
A chemist is interested in the reactivity of iodine
concentrates his study on the decomposition of gaseous
hydrogen iodide (Reaction 1).
2HI g ⇌ H2 g + I2 g
Reaction 1
What is the equilibrium expression for Reaction 1?
(A)
(B)
(C)
(D)
(E)
[H2]2[I2]
[H2]
[H2][I2] / [HI]2
[H2][I2]2
[H2]2[I2]2
69
A chemist is interested in the reactivity of iodine
concentrates his study on the decomposition of gaseous
hydrogen iodide (Reaction 1).
2HI g ⇌ H2 g + I2 g
Reaction 1
An increase in pressure in Reaction 1 would
(A)
(B)
(C)
(D)
(E)
Produce more I-(aq)
Produce more H2
Not affect the system
Drive it to the right
Drive it to the left
70
What is the value of the equilibrium constant for the
following reaction if the equilibrium concentrations of
nitrogen, hydrogen, and ammonia are 1 M, 2 M, and 15 M,
respectively?
N2 g + 3H2 (g) ⇌ 2NH3 g
(A)
(B)
(C)
(D)
(E)
0.035
7.5
28
380
None of the above
71
H2 O + H2 O ⇌ H3 O+ + OH −
The reverse reaction for the one shown above is exothermic.
If the temperature is lowered, what will occur?
(A)
(B)
(C)
(D)
(E)
The pH will decrease
The equilibrium will shift to the right
The concentration of H3O+ ions will increase
The equilibrium will shift to the left
Temperature does not affect the equilibrium
72
CO g + 2H2 g ⇌ CH3 OH(g)
Kp = 14.5 (at 210°C); ΔH0= -128.2 kJ/mol
Equal molar amounts of CO and H2 are sealed in a container and
allowed to react according to the reaction above until equilibrium is
established. The container is then compressed, at constant
temperature, to half its original volume. Which of the following
statements describes what happens when the container is compressed?
(A) When the equilibrium is reestablished, all three species have the
same partial pressure
(B) More moles of H2(g) are present after compression than before
(C) The equilibrium constant changes in such a way as to relieve the
applied pressure
(D) When equilibrium is reestablished, the total pressure in the
container is the same as before the compression
(E) When the equilibrium is reestablished, the partial pressure of
CH3OH(g) is higher than before compression
73
CH3 OH g ⇌ CO g + 2H2 (g)
Kp = 0.069 (at 210°C); ΔH0= +128.2 kJ/mol
A sample of methanol is placed in a sealed container, heated to
210°C, and allowed to establish equilibrium according to the
equation above. The vessel is then heated, at constant pressure,
to 250°C. which of the following will happen when the vessel is
heated?
(A)
(B)
(C)
(D)
The value of the equilibrium constant will increase
The value of the equilibrium constant will decrease
The reaction will produce more moles of CH3OH (g)
The system will relieve the stress by shifting toward the side
with fewer moles of gaseous reaction species
(E) As long as the pressure is constant, the equilibrium need not
shift, and the relative amounts of reactants and products stay
the same
74
Each of the following systems is at equilibrium in a closed
container. A decrease in the total volume of each container will
increase the number of moles of product(s) for which system?
(A)
(B)
(C)
(D)
(E)
2NH3 g ⇌ N2 g + 3H2 (g)
H2 g + Cl2 (g) ⇌ 2HCl (g)
2NO g + O2 (g) ⇌ 2NO2 g
CO g + H2 O(g) ⇌ CO2 g + H2 (g)
Fe3 O4 s + 4H2 (g) ⇌ 3Fe s + 4H2 O(g)
75
For the reaction A + B ⇌ C + D, the equilibrium constant can be
expressed as:
A [B]
(A) K =
C [D]
C [B]
(B) K =
A [D]
C [D]
(C) K =
A [B]
C∙D
(D) K =
A∙B
76
𝐴𝐵 ⇌ 𝐴+ + 𝐵−
A small value for K, the equilibrium constant, indicates that
(A) The concentration of the un-ionized molecules must be
relatively small compared with the ion concentration
(B) The concentration of the ionized molecules must be larger
than the ion concentration
(C) The substance ionizes to a large degree
(D) The concentration of the un-ionized molecules must be
relatively large compared with the ion concentrations
77
A change in which of these conditions will change the K of an
equilibrium given as a starting point?
(A) Temperature
(B) Pressure
(C) Concentration of reactants
(D) Concentration of products
78
If Ca(OH)2 is dissolved in a solution of NaOH, its solubility,
compared with that in pure water, is
(A) Increased
(B) Decreased
(C) unaffected
79
In this equilibrium reaction: A + B ⇌ AB + heat (in a closed
container), how could the forward reaction rate be increased?
I. By increasing the concentration of AB
II. By increasing the concentration of A
III. By removing some of product AB
(A) I only
(B) III only
(C) I and III only
(D) II and III only
(E) I, II, and III
80
For a saturated solution of salt in water, which statement is true?
(A) All dissolving has stopped
(B) Crystals begin to grow
(C) An equilibrium has been established
(D) Crystals of the solute will visibly continue to dissolve
(E) The solute is exceeding its solubility
81
For the following reaction, N2 O4 g ⇌ 2NO2 (g), the Keq
expression is
[N2 O4 ]
(A) Keq =
[NO2 ]
[N2 O4 ]
(B) Keq =
NO2 2
(C) Keq =
[NO2]
[N2O4]
NO2 2
(D) Keq =
[N2 O4 ]
N2 O4 2
(E) Keq =
[NO2 ]
82
What is the Keq for the reaction N2 O4 g ⇌ 2NO2 (g), if at
equilibrium the concentration of N2O4 is 4 x 10-2 mole/liter and
that of NO2 is 2 x 10-2 mole/liter?
(A) 1 x 10-2
(B) 2 x 10-2
(C) 4 x 10-2
(D) 4 x 10-4
(E) 8 x 10-2
83
For the Haber process: N2 + 3H2 ⇌ 2NH3 + heat (at
equilibrium), which of the following statements concerning the
reaction rate is/are true?
I.
The reaction to the right will increase when pressure is
increased
II. The reaction to the right will decrease when the temperature
is increased
III. The reaction to the right will decrease when NH3 is removed
from the chamber
(A) I only
(B) II only
(C) I and II only
(D) II and III only
(E) I, II, and III
84
A small value for Keq indicates that equilibrium occurs
(A) At a low product concentration
(B) At a high product concentration
(C) After considerable time
(D) With the help of a catalyst
(E) With no forward reaction
85
What could be the equilibrium constant for this reaction: aA +
bB ⇌ cC + dD?
CcDd
(A)
AaBb
AaBb
(B)
CcDd
Cc
(C)
Bb
CcDd
(D)
Aa
(E) A
a
B
b
C
c
D
d
86
What occurs when a reaction is at equilibrium and more reactant
is added to the container?
(A) The equilibrium remains unchanged
(B) The forward reaction rate increases
(C) The reverse reaction rate increases
(D) The forward reaction rate decreases
(E) The reverse reaction rate decreases
87
If the following reaction has achieved equilibrium in a closed
system:
N2 O4 g ⇌ 2NO2 g
which of the following is/are increased by decreasing the size of
the container?
I. The value of K
II. The concentration of N2O4(g)
III. The rate of the reverse reaction
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
88
1 N2 g + 3H2 g ⇌ 2NH3 g , Keq = (472°C) = 0.105
2 N2 g + 3H2 (g) ⇌ 2NH3 g , Keq = (448°C) = 50
In comparing the two reactions above, performed at the indicated
temperatures, which of the following is true?
(A) Reaction 1 is favored in the forward direction, and reaction 2
is favored in the reverse direction
(B) Reaction 1 is favored in the reverse direction, and reaction 2 is
favored in the forward direction
(C) Both reactions 1 and 2 are favored in the forward direction
(D) Both reactions 1 and 2 are favored in the reverse direction
(E) Neither reaction favors either the forward or reverse direction
89
2SO3 g ⇌ 2SO2 g + O2 (g)
If the reaction given above is at equilibrium, the result of a
sudden increase in the concentration of O2 will result in
(A) Increased concentration of SO2 and decreased concentration
of SO3
(B) Increased concentration of SO2 and increased concentration
of SO3
(C) Decreased concentration of SO2 and increased concentration
of SO3
(D) Decreased concentration of SO2 and decreased concentration
of SO3
(E) No change in any product or reactant
90
2H2 S g + 3O2 g ⇌ 2SO2 g + H2 O g + heat
For the above reaction, the equilibrium concentration of SO2 can
be increased by
(A) Adding neon gas
(B) Increasing the temperature
(C) Adding a catalyst
(D) Increasing the concentration of H2O(g)
(E) Increasing the concentration of O2(g)
91
2N2 O4 g ⇌ 2NO2 (g)
The following concentration data were gathered for the above reaction
at 5 minute intervals from the start of an experiment:
Time after start of experiment
[N2O4]
[NO2]
0 min (start)
0.00 M
0.50 M
5 min
0.10 M
0.33 M
10 min
0.20 M
0.20 M
15 min
0.25 M
0.15 M
20 min
0.28 M
0.13 M
25 min
0.38 M
0.13 M
If the experiment was carried out in a closed system at constant
temperature, then during which time interval (from the start of the
experiment) did the reaction most likely achieve equilibrium?
(A) 0 min (start) to 5 min
(B) 5 min to 10 min
(C) 10 min to 15 min
(D) 15 min to 20 min
(E) 20 min to 25 min
92
2NOCl g ⇌ 2NO g + Cl2 (g)
Which of the following expressions gives the equilibrium constant
for the reaction above?
[NOCl]
(A)
NO [Cl2 ]
NO 2 [Cl2 ]
(D)
NOCl 2
NO [Cl2 ]
(B)
[NOCl]
NOCl 2
(E)
NO 2 Cl2 2
NOCl 2
(C)
NO 2 [Cl2 ]
93
2NOCl g ⇌ 2NO g + Cl2 (g)
Which of the following changes to the equilibrium would serve to
decrease the concentration of Cl2?
I. The addition of NOCl(g) to the reaction vessel
II. The addition of NO(g) to the reaction vessel
III. A decrease in the volume of the reaction vessel
(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) II and III only
94
Given the reaction A ⟶ B + C, where ΔHrxn is negative, what
effect would increasing the temperature (at constant pressure)
have on the system at equilibrium?
(A) No change
(B) Cannot be determined
(C) Shift to the right
(D) Shift to the left for K < 1 and to the right for K > 1
(E) Shift to the left
95
If the equilibrium constant for the reverse reaction is 9.0 x 10-4,
what is the equilibrium constant for the forward reaction?
(A) 3.0 x 10-2
(B) -3.0 x 10-2
(C) -9.0 x 10-2
(D) 1/9.0 x 10-4
(E) 1/-9.0 x 10-2
96
Given the following reaction at equilibrium:
3H2 g + N2 g ⇌ 2NH3 g + heat energy
Which of the following conditions would shift the equilibrium of
this reaction so that the formation of ammonia is favored?
(A) Increasing the pressure on the reaction
(B) Heating the reaction
(C) Removing the hydrogen gas from the reaction
(D) Adding more ammonia to the reaction
(E) Removing nitrogen gas from the reaction
97
Which factors are equal in a reversible chemical reaction that has
reached equilibrium?
(A) The number of moles of the reactants and products
(B) The potential energies of the reactants and products
(C) The activation energies of the forward and reverse reactions
(D) The rates of reactions for the forward and reverse reactions
(E) The concentrations of the reactants and products
98
Which system at the equilibrium will not be influenced by a
change in pressure?
(A)
(B)
(C)
(D)
(E)
3O2 g ⇌ 2O3 g
N2 g + 3H2 (g) ⇌ 2NH3 (g)
2NO2 g ⇌ N2 O4 (g)
H2 g + I2 (g) ⇌ 2HI (g)
2W g + X g ⇌ Y g + 2Z(s)
99
The equilibrium constant expression for the reaction:
2A g + B g ⇌ 3C g + 2D(g) is written as
(A) Keq =
A 2 [B]
C3D2
(B) Keq =
C3D2
A 2 [B]
(C) Keq =
D2
A 2 [B]
(D) Keq =
A 2 [B]
D2
(E) Keq =
C [D]
A [B]
100
Which will not happen when sodium sulfate is added to a
saturated solution of PbSO4 that is at equilibrium?
2+
PbSO4 s ⇌ Pb
aq + SO4
2−
(aq)
(A) The solubility of the lead sulfate will decrease
(B) The concentration of lead ions will decrease
(C) The reaction will shift to the left
(D) The Ksp value will change
(E) The equilibrium will shift to consume the increase in sulfate
ions
101
Which will happen when sodium sulfate is added to a saturated
solution of CaSO4 that is at equilibrium?
CaSO4 s ⇌ Ca
2+
aq + SO4
2−
(aq)
(A) The solubility of the calcium sulfate will decrease
(B) The concentration of calcium ions will increase
(C) The reaction will shift to the right
(D) The Ksp value will change
(E) The equilibrium will shift to consume the decrease in sulfate
ions
102
At equilibrium
(A) The forward reaction will continue
(B) A change in reaction conditions may shift the equilibrium
(C) The reverse reaction will not continue
(D) Both A and B
103
III. Rates
Questions 1-2 refer to the following
(A)
(B)
(C)
(D)
(E)
An increase in the reactant concentration
An increase in the temperature
A decrease in pressure
Catalysts
pH
1. Increase the number of collisions without
increasing average energy
2. Decreases the activation energy
104
Questions 1-3 refer to the following
1. Indicates the activation energy of the forward reaction
2. Indicates the activation energy of the reverse reaction
3. Indicates the difference between the activation energies for
the reverse and forward reactions and equals the energy
change in the reaction
105
Questions 1-3 refer to the following
(A)
(B)
(C)
(D)
(E)
Ca2+
2−
aq + CO3 (aq) ⇌ CaCO3 s
N2 g + 2O2 (g) ⇌ 2NO2 (g)
4NH3 g + 5O2 g ⇌ 4NO g + 6H2 O(g)
H2 g + I2 (g) ⇌ 2HI(g)
2N𝑎2 O2 s + H2 O l ⇌ NaOH aq + H2 O2 (aq)
1. Reaction rate can be increased by increasing the surface area
of the reactants
2. Increasing the system pressure by decreasing reaction volume
shifts equilibrium to the right
106
Questions 1-4 refer to the following
1.
2.
3.
4.
The activation energy of the forward reaction is shown by
The activation energy of the reverse reaction is shown by
The heat of the reaction for the forward reaction is shown by
The potential energy of the reactants is shown by
107
Questions 1-3 refer to the following
1. Is the activation energy of the reverse reaction
2. Is the enthalpy change of the forward reaction
3. Represents the energy of the activated complex
108
II
I
In a second-order
reaction with respect
to A, when you
double [A], the rate
is quadrupled
BECAUSE
Catalysts decrease
the rate of a
chemical reaction
BECAUSE
The rate equation r = k[A]2 for
such a reaction
Catalysts decrease the
activation energy
109
II
I
Reactions happen
faster at higher
temperature
BECAUSE
As temperature increases,
there is also an increase in the
number of collisions with the
required activation energy for
a reaction to occur
A catalyst accelerates
a chemical reaction
BECAUSE
A catalyst lowers the
activation energy of the
reaction
110
II
I
Increasing the
concentration of a
gaseous reactant
typically increases
the reaction rate
BECAUSE
The reaction rate is increased
as the energy per molecular
collision increases
The rate of a reaction
is accelerated by
increasing
temperature
BECAUSE
A large equilibrium constant
favors the formation of
product
111
II
I
The addition of a
catalyst will decrease
the H for a reaction
BECAUSE
A catalyst provides an
alternative reaction pathway
with a lower activation energy
Chemical reactions
slow down with
lower temperature
BECAUSE
The energy barrier for the
formation of products
decreases with decreasing
temperature
Adding more
reactants will speed
up a reaction
BECAUSE
The reactants will collide less
frequently
112
In the following diagram, which labeled arrow represents the
activation energy for the reverse reaction?
(A) A
(B) B
(C) C
(D) D
113
According to the chemical kinetic theory, a reaction can occur
(A) If the reactants collide with the proper orientation
(B) If the reactants possess sufficient energy of collision
(C) If the reactants are able to form a correct transition state
(D) All of the above
114
Which of the following is most likely to increase the rate of a
reaction?
(A) Decreasing the temperature
(B) Increasing the volume of the reaction vessel
(C) Reducing the activation energy
(D) Decreasing the concentration of the reactant in the reaction
vessel
115
All of the following are true statements concerning catalysts
EXCEPT
(A) A catalyst will speed the rate-determining step
(B) A catalyst will be used up in a reaction
(C) A catalyst may induce steric strain in a molecule to make it
react more easily
(D) A catalyst will lower the activation energy of a reaction
116
For the reaction: A + B ⟶ C, determine the order of the
reaction with respect to B from the information given below:
Initial [A]
Initial [B]
1.00
1.00
1.00
2.00
2.00
2.00
Initial rate of
formation of C
2.0
8.1
15.9
(A) Zero-order
(B) First-order
(C) Second-order
(D) Third-order
(E) Fourth-order
117
A catalyst
(A) Changes ΔG for an equation
(B) Acts by increasing the rate of the forward reaction more than
the reverse reaction
(C) Raises the equilibrium constant of a system
(D) May have a molecular weight as low as 1 or higher than
200.000
(E) Does not react chemically during the course of a reaction
118
Which of the following statements does not accurately describe
the action of a catalyst?
(A) A catalyst causes a reaction to proceed at a faster rate
(B) A catalyst lowers the activation energy of a reaction
(C) A catalyst affects the rate of both the forward and the reverse
reaction
(D) A catalyst increases the rate constant of a reaction
(E) A catalyst increases the equilibrium constant of a reaction
119
A possible mechanism for the reaction of carbon monoxide with
nitrogen dioxide is
2NO2 g ⟶ NO3 g + NO(g) (slow)
NO3 g + CO(g) ⟶ NO2 g + CO2 (g) (fast)
Which of the following could be the rate law for this reaction?
(A) Rate = k[NO2]
(B) Rate = k[NO2]2
(C) Rate = k[NO3][CO]
(D) Rate = k[NO3][CO][NO2]2
(E) Rate = k[NO][NO3]/[NO2]2
120
The addition of a catalyst to a reaction
(A) Changes the enthalpy
(B) Changes the entropy
(C) Changes the nature of the products
(D) Changes the activation energy
121
An increase in concentration
(A) Is related to the number of collisions directly
(B) Is related to the number of collisions inversely
(C) Has no effect on the number of collisions
122
At the beginning of a reaction, the reaction rate for the reaction is
(A) Largest, then decreasing
(B) Largest and remains constant
(C) Smallest, then increasing
(D) Smallest and remains constant
123
The reaction rate law applied to the reaction aA + bB ⟶ AB
gives the expression
(A) Rate ∝ [A]b[B]a
(B) Rate ∝ [AB]a[A]b
(C) Rate ∝ [B]a[AB]b
(D) Rate ∝ [A]a[B]b
124
In this reaction: XClO3 + A ⟶ XCl + O2 (g), which substance is
the catalyst?
(A) X
(B) XClO3
(C) A
(D) XCl
(E) O2
125
In the reaction of zinc with dilute HCl to form H2, which of the
following will increase the reaction rate?
I. Increasing the temperature
II. Increasing the exposed surface of zinc
III. Using a more concentration solution of HCl
(A) I only
(B) II only
(C) I and III only
(D) II and III only
(E) I, II, and III
126
How can the addition of a catalyst affect an exothermic reaction?
I. Speed up the reaction
II. Slow down the reaction
III. Increase the amount of product formed
(A) I only
(B) II only
(C) I and II only
(D) II and III only
(E) I, II, and III
127
Which of the following statements is true?
(A) A catalyst cannot lower the activation energy
(B) A catalyst can lower the activation energy
(C) A catalyst affects only the activation energy of the forward
reaction
(D) A catalyst affects only the activation energy of the reverse
reaction
(E) A catalyst is permanently changed after the activation energy
is reached
128
Which of the following statements is NOT true regarding the
activated complex?
(A) It represents the highest energy state achieved during the
course of a reaction
(B) It is not consumed during the course of a reaction
(C) It is very unstable
(D) It is formed before reactant bonds are completely broken
(E) It is formed before product bonds are completely formed
129
2NOCl g ⇌ 2NO g + Cl2 (g)
Which of the following is true of the reaction above as it proceeds
in the forward direction?
(A) NO(g) is produced at the same rate that NOCl(g) is consumed
(B) NO(g) is produced at half the rate that NOCl(g) is consumed
(C) NO(g) is produced at twice the rate that NOCl(g) is consumed
(D) Cl2(g) is produced at the same rate that NOCl(g) is consumed
(E) Cl2(g) is produced at twice the rate that NOCl(g) is consumed
130
Which of the following statements is NOT correct regarding
chemical catalysts?
(A) They are not consumed during the chemical reaction
(B) They cannot make nonspontaneous reactions occur
(C) They do not have to be the same phase as the reactant
molecules
(D) They shift equilibrated reactions to the product’s side
(E) Enzymes are biological catalysts
131
In a reaction the potential energy of the reactants is 40 kJ/mol,
the potential energy of the products is 10 kJ/mol and the
potential energy of the activated complex is 55 kJ/mol. What is
the activation energy for the reverse reaction?
(A) 45 kJ/mol
(B) -30 kJ/mol
(C) 15 kJ/mol
(D) 35 kJ/mol
(E) -55 kJ/mol
132
Given the reaction: Zn s + 2HCl aq ⟶ ZnCl2 aq + H2 (g)
Why is the reaction slower when a single piece of zinc is used
than when powdered zinc of the same mass is used?
(A) The powdered zinc is more concentrated
(B) The single piece of zinc is more reactive
(C) The powdered zinc requires less activation energy
(D) The powdered zinc generates more heat energy
(E) The powdered zinc has a greater surface area
133
Which takes place when a catalyst is added to a reaction at
equilibrium?
(A) The point of equilibrium is shifted to the right
(B) The point of equilibrium is shifted to the left
(C) The forward and reverse reaction rates are increased
unequally
(D) The forward and reverse reaction rates are increased equally
(E) The value of ΔH has the same magnitude but a different sign
134
As the frequency and the number of effective collisions between
reacting particles increases, the rate of the reaction
(A) Increases
(B) Decreases
(C) Remains the same
(D) Approaches zero
(E) None of the above
135
A catalyst is added to a system at equilibrium. The concentration
of the reactants will then
(A) decrease
(B) increase
(C) Remain the same
(D) Approach zero
(E) None of the above
136
Which of the following will not be changed by the addition of a
catalyst to a reaction at equilibrium?
I. The point of equilibrium
II. The heat of reaction, ΔH
III. The potential energy of the products
(A) I only
(B) II only
(C) I and II only
(D) II and III only
(E) I, II, and III
137
Which of the following processes will decrease the rate of a
chemical reaction?
I. Using highly concentrated reactants
II. Decreasing the temperature by 25 K
III. Stirring the reactants
(A) I only
(B) II only
(C) I and III only
(D) II and III only
(E) I, II, and III
138