Unit 5 Practice Questions
I.
Thermochemistry
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Enthalpy change
Entropy change
Gibbs free energy change
Activation energy
Specific heat capacity
1. Is the amount of energy that must be added to
raise the temperature of 1 gram of a substance to
1oC
2. Its value indicates the spontaneity of a reaction
3. Its value indicates whether a reaction is
endothermic or exothermic
1
Questions 1-4 refer to the following:
(A)
(B)
(C)
(D)
(E)
Positive DH
Negative DH
Positive DG
Negative DG
Positive DS
1.
2.
3.
4.
Describes a spontaneous reaction
Describes an endothermic reaction
Describes a nonspontaneous reaction
Is multiplied by temperature in the equation that
calculates free energy
2
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Gibbs free energy
Heat of formation
Enthalpy change
Entropy
Kinetic energy
1. Value that determines whether a reaction is
spontaneous
2. Quantity that determines whether a reaction is
exothermic or endothermic
3. Indicates the degree of disorder in a system
3
II
I
An exothermic
reaction releases
more heat than it
absorbs
An exothermic
reaction has a
negative value for
DH
BECAUSE
The potential energy of the
products is greater than
that of the reactants
BECAUSE
In an exothermic
reaction the products
have less potential
energy than the
reactants
4
II
I
If a reaction is
exothermic, it
always proceeds
spontaneously
Ice melting is an
endothermic
process
BECAUSE
The universe favors a
negative enthalpy change
BECAUSE
Heat must be absorbed
by ice if it is to melt
5
II
I
An increase in
entropy leads to a
decrease of
randomness
A gas is more
random than a
liquid
BECAUSE
The lower energy state of
ordered crystals has high
entropy
BECAUSE
Entropy increases from
gas to liquid
6
II
I
An exothermic
reaction has a
positive DH
The entropy of a
solid increases
when it is
dissolved in
solvent
BECAUSE
Heat must be added to the
system for the reaction to
occur
BECAUSE
It becomes less ordered
7
II
I
An endothermic
reaction can be
spontaneous
When a salt
dissolves in water, S
for the process is
positive
BECAUSE
BECAUSE
Both enthalpy and entropy
changes affect the value of
a reaction’s Gibbs free
energy
for a salt sample, aqueous
ions have a greater entropy
than ions in a solid.
8
II
I
Exothermic
reactions absorb
heat
When two
elements react
exothermically to
form a compound,
the compound
should be relatively
stable
BECAUSE
BECAUSE
Breaking covalent bonds
always requires energy.
The release of energy from
a combination reaction
indicates that the
compound formed is at a
lower energy level than the
reactants and thus
relatively stable.
9
II
I
If the heat of
formation of a
compound is a
large number
preceded by a
minus sign, the
reaction is
exothermic
BECAUSE
The First Law of
Thermodynamics states
that a negative heat of
formation is associated
with an exothermic
reaction.
10
II
I
The ΔHreaction of a
particular reaction
can be arrived at by
the summation of
the ΔHreaction values
of two or more
reactions that,
added together,
give the ΔHreaction of
the particular
reaction
BECAUSE
Hess’s Law conforms to the
First Law of
Thermodynamics, which
states that the total energy
of the universe is a
constant.
11
Which of the following demonstrates a decrease in
entropy?
(A)
(B)
(C)
(D)
(E)
Dissolving a solid into solution
An expanding universe
Burning a log in a fireplace
Raking up leaves into a trash bag
Spilling a glass of water
12
When one mole of sulfur burns to form SO2, 1300
calories are released. When one mole of sulfur
burns to form SO3, 3600 calories are released. What
is the DH when one mole of SO2 is burned to form
SO3?
(A)
(B)
(C)
(D)
(E)
3900 cal
-1950 cal
1000 cal
-500 cal
-2300 cal
13
10 g of liquid at 300 K is heated to 350 K. The liquid
absorbs 6 kcals. What is the specific heat of the
liquid (in cal/goC)?
(A)
(B)
(C)
(D)
(E)
6
12
60
120
600
14
Which of the following is NOT a true statement
about the entropy of a system?
(A) Entropy is a measure of the randomness in a
system
(B) The entropy of an amorphous solid is greater
than that of a crystalline solid
(C) The entropy of a spontaneous reaction cannot
decrease
(D) The entropy of an isolated system will
spontaneously increase or remain constant
(E) The entropy of a liquid is generally greater than
that of a solid
15
The combustion of octane, C8H18, has DH < 0 and DS
> 0. Which of the following statements is FALSE
regarding the combustion of octane?
(A) The reaction is spontaneous at room
temperature
(B) The reaction is spontaneous at all temperatures
(C) The reaction products are carbon dioxide and
water vapor
(D) The reaction is a redox process
(E) The reaction is endothermic at room
temperature
16
2Na(s) + Cl2
2NaCl(s) + 822 kJ
How much heat is released by the above reaction if
0.5 mole of sodium reacts completely with
chlorine?
(A)
(B)
(C)
(D)
(E)
205 kJ
411 kJ
822 kJ
1,644 kJ
3,288 kJ
17
This question pertains to the reaction represented
by the following equation:
2NO(g) + O2
2NO2(g) + 150 kJ
Suppose that 0.8 mole of NO is converted to NO2 in
the above reaction. What amount of heat will be
evolved?
(A)
(B)
(C)
(D)
(E)
30 kJ
60 kJ
80 kJ
130 kJ
150 kJ
18
Based on the information shown, each of the
following equations represents a reaction in which
the change in entropy, ΔS, is positive EXCEPT
(A)
(B)
(C)
(D)
(E)
CaCO3(s)
CaO(s) + CO2(g)
Zn(s) + 2H+(aq)
H2(g) + Zn2+(aq)
2C2H6(g) + 7O2(g)
4CO2(g) + 6H2O(g)
NaCl(s)
Na+(aq) + Cl-(aq)
N2(g) + 3H2(g)
2NH3(g)
19
What is the ΔH0 value for the decomposition of
sodium chlorate, given the following information?
3
NaClO3 (s) ® NaCl(s) + O2 (g)
2
(ΔH0f values: NaClO3(s) = -358 J/mol,
NaCl(s) = -410 J/mol, O2(g) = 0 J/mol
(A)
(B)
(C)
(D)
(E)
52.0 J
-52.0 J
768 J
-768 J
3 (768 J)
2
20
In the graphic representation of the energy contents
of the reactants and the resulting products in an
exothermic reaction, the energy content would be
(A)
(B)
(C)
(D)
Higher for the reactants
Higher for the products
The same for both
Impossible to determine
21
To heat 10.0 grams of water from 4°C to 14°C
requires
(A)
(B)
(C)
(D)
10.0 J
4.18 J
418. J
4180. J
22
A synthesis reaction will occur spontaneously after
the activation energy is provided if the heat of
formation of the product is
(A)
(B)
(C)
(D)
Large and negative
Small and negative
Large and positive
Small and positive
23
Enthalpy is the expression for the
(A)
(B)
(C)
(D)
Heat content
Energy state
Reaction rate
Activation energy
24
A ΔHreaction of -100 kJ/mole indicates the reaction is
(A)
(B)
(C)
(D)
Endothermic
Unstable
In need of a catalyst
exothermic
25
According to the Kinetic-Molecular Theory,
molecules increase in kinetic energy when they
(A) Are mixed with other molecules at lower
temperature
(B) Are frozen into a solid
(C) Are condensed into a liquid
(D) Are heated to a high temperature
(E) Collide with each other in a container at a lower
temperature
26
The two most important considerations in deciding
whether a reaction will occur spontaneously are
(A) The stability and state of the reactants
(B) The energy gained and the heat evolved
(C) A negative value for ΔH and a positive value for
ΔS
(D) A positive value for ΔH and a negative value for
ΔS
(E) The endothermic energy and the structure of
the products
27
Which value best determines whether a reaction is
spontaneous?
(A)
(B)
(C)
(D)
(E)
Change in Gibbs free energy, ΔG
Change in entropy, ΔS
Change in kinetic energy, ΔKE
Change in enthalpy, ΔH
Change in heat of formation, ΔH0f
28
Which of these statements is NOT correct?
(A) In an exothermic reaction, ΔH is negative and
the enthalpy decreases.
(B) In an endothermic reaction, ΔH is positive and
the enthalpy increases.
(C) In a reaction where ΔG is negative, the forward
reaction is spontaneous.
(D) In a reaction where ΔG is positive, ΔS may also
be positive.
(E) In a reaction where ΔH is positive and ΔS is
negative, the forward reaction is spontaneous.
29
How much heat energy is released when 8 grams of
hydrogen are burned? The thermal equation is:
2H2(g) +O2(g)
(A)
(B)
(C)
(D)
(E)
2H2O(g) + 483.6 kJ
241.8 kJ
483.6 kJ
967.2 kJ
1,934 kJ
3,869 kJ
30
S + O2
2SO2 + O2
SO2
2SO3
DH = -297 kJ
DH = -198 kJ
Given the above thermochemical reactions, what is
the heat of reaction for the formation of SO3
provided below?
S + 3/2 O2
SO3
(A)
(B)
(C)
(D)
(E)
-495 kJ
-396 kJ
-198 kJ
+99 kJ
+198 kJ
31
Determine the heat of reaction for the combustion
of sulfur dioxide:
2SO2 + O2
2SO3
Given the following thermochemical equations:
I. S8 + 8O2
8SO2
DH = -2374.6 kJ
II. S8 + 12O2
8SO3
DH = -3165.8 kJ
(A)
(B)
(C)
(D)
(E)
-5540.4 kJ
-1385.1 kJ
-791.2 kJ
-197.8 kJ
-791.2 kJ
32
When the temperature of a 20-gram sample of
water is increased from 10oC to 30oC, the heat is
transferred to the water is
(A)
(B)
(C)
(D)
(E)
600 calories
400 calories
200 calories
30 calories
20 calories
33
The change in heat energy for a reaction is best
expressed as a change in
(A)
(B)
(C)
(D)
(E)
Enthalpy
Absolute temperature
Specific heat
Entropy
Kinetic energy
34
The heat capacity for aluminum is 0.89 J/goC, for
iron is 0.45 J/goC, and for zinc is 0.39 J/goC. If 100 J
of heat energy was added to a 10.0 g sample of
each of the metals, which of the following would be
true?
(A)
(B)
(C)
(D)
Al would have the largest temperature increase
Fe would have the largest temperature increase
Zn would have the largest temperature increase
Fe and Zn would have the same temperature
increase
(E) All three metals would have the same
temperature increase
35
Which of the following forward processes produces
a decrease in entropy?
I. H2O(g)
H2O (l)
II. Fe2+(aq) + S2- (aq)
FeS(s)
III. 2SO3(g)
2SO2(g) + O2(g)
(A)
(B)
(C)
(D)
(E)
I only
III only
I and II only
II and III only
I, II, and III
36
If 1 mole of O2(g) is consumed in the reaction given
below, how much energy is released?
CH4(g) + 2O2(g)
(A)
(B)
(C)
(D)
(E)
CO2(g) + 2H2O(g) + 800 kJ
200 kJ
400 kJ
800 kJ
1,200 kJ
1,600 kJ
37
In which of the following processes is entropy
increasing?
(A)
(B)
(C)
(D)
(E)
N2(g) + 3Cl2(g)
2NCl3(g)
H2O(g)
H2O(l)
2H2O(l)
2H2(g) + O2(g)
CO(g) + 2H2(g)
CH3OH(l)
2NO2(g)
N2O4(g)
38
Which of the following reactions shows a decrease
in entropy?
(A)
(B)
(C)
(D)
(E)
C (s) + 2H2(g)
CH4(g)
H2O(g)
H2(g) + 1/2 O2(g)
2NI3(s)
N2(g) + 3I2(g)
2O3(g)
3O2(g)
None of the above
39
At which temperature does a water sample have
the highest kinetic energy?
(A)
(B)
(C)
(D)
(E)
0 degrees Celsius
100 degrees Celsius
0K
100 K
273 K
40
If the free energy change accompanying a reaction
is negative
(A) The reaction can occur spontaneously
(B) The reaction can be used to do work by driving
other reactions
(C) The entropy must always be negative
(D) Both A and B
41
A 50 g sample of metal was heated to 100oC and
then dropped into a beaker containing 50 g of water
at 25oC. If the specific heat capacity of the metal is
0.25 cal/goC, what is the final temperature of the
water?
(A)
(B)
(C)
(D)
27oC
40oC
60oC
86oC
42
How many joules of heat are released by a 150gram sample of water that cools from 25oC to 5oC?
(C for water is 4.18 J/gK)
(A)
(B)
(C)
(D)
(E)
78,375 joules
83.6 joules
720 joules
627 joules
12,540 joules
43
Which process below has been described correctly for
a temperature above 274K?
(A)
(B)
(C)
(D)
(E)
H2O(l)
H2O(l)
H2O(g)
H2O(s)
H2O(s)
H2O(s) is exothermic and spontaneous
H2O(s) is endothermic and spontaneous
H2O(l) is endothermic and spontaneous
H2O(l) is endothermic and spontaneous
H2O(l) is exothermic and spontaneous
44
Calculate the heat for the overall reaction:
Mg + ½ O2
MgO
Given the heats of reaction below:
Mg + 2HCl
MgCl2 + H2
DH = -143kJ
MgO + 2HCl
MgCl2 + H2O
DH = -216kJ
H2 + ½ O2
H2O
DH = -285kJ
(A)
(B)
(C)
(D)
(E)
-644 kJ
-212 kJ
+644 kJ
-74 kJ
+74 kJ
45
What is the value of DH for the reaction:
X + 2Y
2Z
(W + X
(2W + 3X
(A)
(B)
(C)
(D)
(E)
2Y
DH = -200 kcal)
2Z + 2Y
DH = -150 kcal)
-550 kcal
+50 kcal
-50 kcal
-350 kcal
+250 kcal
46
Calculate the enthalpy of formation of a mole of N (g)
in the following reaction:
N2 (g)
2N (g)
DH = 945.2 kJ
(A)
(B)
(C)
(D)
-945.2 kJ/mol
0.0 kJ/mol
472.6 kJ/mol
945.2 kJ/mol
47
Which units could be used to express the amount of
energy absorbed or released during a chemical
reaction?
(A)
(B)
(C)
(D)
(E)
Degree and gram
Torr and mmHg
Gram and liter
Calorie and joule
Meter and cm3
48
How much heat is required to raise the temperature
of 85 grams of water from 280 K to 342 K?
(A)
(B)
(C)
(D)
(E)
5,270 J
355 J
259 J
151 J
22,029 J
49
Which set of conditions below guarantees that a
reaction will be spontaneous?
(A)
(B)
(C)
(D)
(E)
DH(+) and DS(-)
DH(-) and DS(+)
DH(+) and DS(+) at a low temperature
DH(-) and DS(+) at a high temperature
DG(+)
50
Which statement is incorrect regarding energy?
(A)
(B)
(C)
(D)
(E)
Energy can be given off in a reaction
Energy can be gained in a reaction
Energy cannot be created or destroyed
Energy can take various forms
Energy has mass and takes up space
51
A process involving no heat exchange is known as
(A)
(B)
(C)
(D)
An isothermal process
An isobaric process
An adiabatic process
An isometric process
52
What is the heat capacity of a 10 g sample that has
absorbed 100 cal over a temperature change of
30oC?
(A)
(B)
(C)
(D)
0.333 cal/goC
0.666 cal/goC
3 cal/goC
300 cal/goC
53
What is the value for DH for the reaction:
D+A+B
F
(A + B
(D + ½ B
(F + ½ B
(A)
(B)
(C)
(D)
(E)
C
DH = -390 kJ)
E
DH = -280 kJ)
C+E
DH = -275 kJ)
-165 kJ
+385 kJ
-395 kJ
-945 kJ
+400 kJ
54
From the heats of reaction of these individual
reactions:
A+B
2C
DH = -500 kJ)
(D + 2B
E
DH = -700 kJ)
(2D + 2A
F
DH = +50 kJ)
Find the heat of reaction for F + 6B
(A)
(B)
(C)
(D)
(E)
2E + 4C
+450 kJ
-1100 kJ
+2300 kJ
-350 kJ
-2450 kJ
55
Which of the following demonstrates DS(-)?
I. Raking up leaves
II. Boiling a liquid
III. Emptying a box of confetti onto the floor
(A)
(B)
(C)
(D)
(E)
I only
II only
I and II only
I and III only
II and III only
56
Which process would have a positive value for the
change in entropy?
I. The expansion of the universe
II. The condensation of a liquid
III. A food fight at a school cafeteria
(A)
(B)
(C)
(D)
(E)
I only
II only
III only
II and III only
I and III only
57
II. Phase Changes
Questions 1-4 refer to the following:
(A) Sublimation
(B) Deposition
(C) Vaporization
(D) Condensation
(E) freezing
1.
2.
3.
4.
Solid to gas
Gas to solid
Liquid to gas
Liquid to solid
58
Questions 1-4 refer to the following:
(A)
(B)
(C)
(D)
(E)
N2O4(g) + heat
2NO2(g)
I2(s)
I2(g)
CHCl3(l)
CHCl3(g)
Br2(s)
Br2(l)
O2(g)
O2(l)
1. At constant pressure, requires a decrease in heat to
occur
2. Is an example of sublimation
3. Produces a decrease in system entropy
4. Enthalpy change for the process can equal heat of
fusion for the process
59
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
Sublimation
Condensation
Evaporation
Deposition
Melting
1. Gas
2. Gas
3. Solid
solid
liquid
gas
60
I
II
BECAUSE
When a sample of
water freezes, the
process is
exothermic
Water boils at a
lower temperature
at high altitude
than at low altitude
ice is at a lower potential
energy state than water
BECAUSE
The vapor pressure of
water is lower at higher
altitude
61
I
II
BECAUSE
A network solid has
a high melting
point
hydrogen bonds are more
difficult to break than
covalent bonds
A pot of water will
boil above 100oC at
high elevations
the average kinetic energy
of molecules must increase
as the pressure on them
increases
BECAUSE
62
I
At 1 atm, pure
water can boil at a
temperature less
than 273K
CO2 is able to
sublimate at
atmospheric
pressure
II
BECAUSE
BECAUSE
Water boils when the vapor
pressure of the water is
equal to the atmospheric
pressure
Its liquid form is impossible
to produce
63
I
II
BECAUSE
As ice absorbs heat
and begins to melt,
its temperature
remains constant
320 calories or
1.34 × 103 joules of
heat will melt 4
grams of ice at 0°C
The absorbed heat is
consumed by the breaking
of intermolecular reactions
BECAUSE
The heat of fusion of water
is 80 calories per gram or
3.34 × 102 joules per gram.
64
The process in which water vapor changes phase to
become a liquid is called
(A)
(B)
(C)
(D)
(E)
Deposition
Sublimation
Vaporization
Fusion
Condensation
65
Which of the following indicates the relative
randomness of molecules in the three states of
matter?
(A)
(B)
(C)
(D)
(E)
Solid > liquid > gas
Liquid < solid < gas
Liquid > gas > solid
Gas > liquid > solid
None of the above
66
Which of the following generalizations CANNOT be
made about the phase change of a pure substance
from solid to liquid?
(A)
(B)
(C)
(D)
(E)
It involves a change in potential energy
It involves no change in temperature
It involves a change in kinetic energy
It involves a change in entropy
It may occur at different temperatures for
different compounds
67
A substance possessing a characteristically low
vapor pressure can be expected to have
(A)
(B)
(C)
(D)
(E)
Extremely weak intermolecular forces
A relatively small heat of vaporization
A relatively high boiling point
A relatively high rate of evaporation
A significantly high percentage of molecules
that have high kinetic energy
68
What is the correct term for the phase change from
gas directly to solid?
(A)
(B)
(C)
(D)
(E)
Deposition
Sublimation
Liquefaction
Fusion
Vaporization
69
If 10.0 grams of ice melts at 0°C, the total quantity
of heat absorbed is
(A)
(B)
(C)
(D)
10.0 J
334 J
3,340 J
33,400 J
70
A liquid will boil when
(A) Enough salt has been added to it
(B) The vapor pressure of the liquid is equal to the
atmospheric or surrounding pressure
(C) The vapor pressure of the liquid reaches 760
mmHg
(D) Conditions favor the liquid’s molecules to be
closer together
(E) It has been brought up to a higher elevation
71
Calculate the number of joules required to
completely evaporate 18 grams of water at 98oC.
(Hv = 2259 J/g and C = 4.18 J/gK)
(A)
(B)
(C)
(D)
(E)
40812 joules
40512 joules
150 joules
40662 joules
6.12 x 106 joules
72
Which sample demonstrates particles arranged in a
regular geometric pattern?
(A)
(B)
(C)
(D)
(E)
CO2(g)
CO2(s)
CO2(l)
CO2(aq)
None of the above
73
Which phase change is described correctly?
(A)
(B)
(C)
(D)
(E)
Solid to gas is called deposition
Gas to solid is called sublimation
Liquid to solid is called freezing
Solid to liquid is called vaporization
Liquid to gas is called condensation
74
A solid, liquid and gas can exist together at the
(A)
(B)
(C)
(D)
(E)
Sublimation point
Triple point
Boiling point
Freezing point
Melting point
75
Which of the following solids are known to undergo
sublimation?
I. CO2
II. I2
III. naphthalene
(A)
(B)
(C)
(D)
(E)
I only
II only
I and II only
II and III only
I, II and III
76
Refer to the following choices:
I. solid to liquid
II. Liquid to gas
III. Solid to gas
Which phase change above is endothermic?
(A)
(B)
(C)
(D)
(E)
I only
II only
III only
II and III only
I, II and III
77
III. Gases
Questions 1-4 refer to the following:
(A) Boyle’s Law
(B) Charles’ Law
(C) Avogadro’s Principle
(D) Ideal Gas Law
(E) Dalton’s Law
1. Total pressure of a gaseous mix is equal to the sum
of the partial pressures
2. Volume is inversely proportional to pressure
3. Volume is directly proportional to temperature
4. All gases have the same number of moles in the
same volume at constant temperature and
pressure
78
Questions 1-3 refer to the following:
(A)
(B)
(C)
(D)
(E)
He at 100oC and 1 atm
He at 25oC and 1 atm
Ar at 25oC and 1 atm
Ar at 25oC and 2 atm
Ar at 0oC and 1 atm
1. Has the highest molecular speed
2. Has the lowest kinetic energy
3. Occupies the largest volume
79
II
I
Increasing the
pressure on a gas
forces the gas to
occupy a smaller
volume
The relationship
between pressure
and volume is
considered to be
an inverse
relationship
BECAUSE
Gases are compressible
BECAUSE
As pressure increases on
a gas, the volume of the
gas will decrease
80
II
I
Nitrogen gas will
have a greater rate
of effusion than
oxygen gas
The ideal gas law
does not hold
under low
temperatures and
high pressure
BECAUSE
Lighter, less dense gases
travel faster than heavier,
more dense gases
BECAUSE
Interactions between
particles cannot be
neglected under these
conditions
81
II
I
When an ideal gas
is cooled, its
volume will
increase
In the kinetic
theory of gases,
collisions between
gas particles and
the walls of the
container are
considered elastic
BECAUSE
BECAUSE
Temperature and volume
are proportional
Gas molecules are
considered pointlike,
volumeless particles with
no intermolecular forces
and in constant, random
motion
82
I
Hydrogen gas (H2)
is considered a
perfectly ideal gas
A gas heated from
10°C to 100°C at
constant pressure
will increase in
volume
II
BECAUSE
BECAUSE
hydrogen atoms interact
with each other via
hydrogen bonds
As Charles’s Law states,
if the pressure remains
constant, the volume
varies directly as the
absolute temperature
varies.
83
II
I
If an ideal gas is
located in a closed
container and
temperature is
increased, the
average speed of
the molecules will
always increase as
well
BECAUSE
For an ideal gas,
temperature and moles of
gas are inversely
proportional.
84
II
I
For an ideal gas,
pressure and
volume have no
relationship
BECAUSE
according to the ideal gas
law, temperature and
volume are directly
proportional when other
variables are held constant.
At isothermal and
isobaric conditions,
helium effuses
faster than neon
BECAUSE
Neon has a higher molar
mass than helium
85
If the pressure of a gas is doubled at constant
temperature, the volume will be
(A)
(B)
(C)
(D)
(E)
4 times the original
2 times the original
½ of the original
¼ of the original
1/8 of the original
86
Given equal conditions, which gas below is expected
to have the greatest rate of effusion?
(A)
(B)
(C)
(D)
(E)
H2
Ar
Kr
F2
Cl2
87
Which fraction would be used to find the new volume
of a gas at 760 torr under its new pressure at 900 torr
if the temperature is kept constant?
(A)
(B)
(C)
(D)
(E)
900/760
1.18
760/900
658.7/798.7
798.7/658.7
88
Which of the following statements is not part of the
kinetic molecular theory?
(A) The average kinetic energy of gas molecules is
proportional to temperature
(B) Attractive and repulsive forces are present
between gas molecules
(C) Collisions between gas molecules are perfectly
elastic
(D) Gas molecules travel in a continuous, random
motion
(E) The volume that gas molecules occupy is minimal
compared to the volume in which the gas is
contained
89
What is the volume of 2.3 moles of an ideal gas at 300
K and a pressure of 1.1 atmospheres?
(A) (2.3 moles)(0.0820 Latm/molK)(300 K)
(1.1 atm)
(B)
(1.1 atm)
(2.3 moles)(0.0820 Latm/molK)(300 K)
(C) (2.3 moles)(0.0820 Latm/molK)
(300 K)(1.1 atm)
(D) (300 K)(0.0820 Latm/molK)
(2.3 moles)(1.1 atm)
(E) (2.3 moles)(1.1 atm)(300 K)
(0.0820 Latm/molK)
90
One mole of an ideal gas at STP has its temperature
changed to 15oC and its pressure changed to 700 torr.
What is the new volume of this gas?
(A) (760 torr)(22.4 L)(288 K)
(273 K)(700 torr)
(B)
(273 K)(700 torr)
(760 torr)(22.4 L)(288 K)
(C) (760 torr)(22.4 L)(273 K)
(288 K)(700 torr)
(D) (700 torr)(22.4 L)(287 K)
(273 K)(760 torr)
(E) (760 torr)(1.0 L)(288 K)
(273 K)(700 torr)
91
Ideal gases
(A)
(B)
(C)
(D)
(E)
Have forces of attraction between them
Are always linear in shape
Never travel with a straight line motion
Have molecules that are close together
Have low masses and are spread far apart
92
A mixture of gases exists in a sealed container with
the following percentages: helium 40%, neon 50%,
argon 10%. If the total pressure of the gases is 1100
torr, then which of the following is true about these
gases?
(A) Volume and temperature have an inversely
proportional relationship
(B) Volume and pressure have a direct relationship
(C) The partial pressure of the neon gas is 550 torr
(D) The partial pressure of the argon gas is 100 torr
(E) The partial pressures of the gases cannot be
calculated with the given information
93
An ideal gas at STP occupies 22.4 liters. If the pressure
on the gas is increased to 1000 torr and the
temperature of the gas is reduced to 250 K, what can
be said about the gas?
(A)
(B)
(C)
(D)
The number of moles of gas has changed
The volume of the gas has increased
The volume of the gas has decreased
The pressure and the temperature have an
inversely proportional relationship
(E) None of the above
94
Which is inconsistent with the Kinetic Molecular
Theory?
(A) Gas molecules have forces of attraction for each
other
(B) Gas molecules move in a random, straight-line
motion
(C) Gas molecules have a negligible volume
compared to the volume they occupy
(D) Collisions between gas molecules lead to a
transfer of energy that is conserved
(E) All of the above statements are correct
95
Which laws can be used to calculate changes in
volume with changes in pressure at constant
temperature?
I. Boyle’s Law
II. Charles’ Law
III. Combined Gas Law
(A)
(B)
(C)
(D)
(E)
I only
II only
II and III only
I and III only
I and II only
96
Inelastic collisions occur in
I. Real gases
II. Ideal gases
III. Fusion reactions
(A)
(B)
(C)
(D)
(E)
I and II
II and III
I and III
I only
II only
97
When a fixed amount of gas has its Kelvin
temperature doubled and its pressure doubled, the
new volume of the gas is
(A)
(B)
(C)
(D)
(E)
Four times greater than its original volume
Twice its original volume
Unchanged
One-half its original volume
One-fourth its original volume
98
A flask contains three times as many moles of H2 gas
as it does O2 gas. If hydrogen and oxygen are the only
gases present, what is the total pressure in the flask if
the partial pressure due to oxygen is P?
(A)
(B)
(C)
(D)
(E)
4P
3P
4/3 P
¾P
7P
99
Boyle’s Law can be used for which of the following?
(A) Predicting the expected volumes of two party
balloons
(B) Predicting the relative pressures inside a hot air
balloon
(C) Predicting the change in volume of an inflatable
toy from summer to winter
(D) Predicting the height of a mercury barometer
column in a low-pressure system
(E) Predicting the change in volume of a party
balloon inside a bell jar as a vacuum is being
drawn
100
A sample of argon occupies 50 L at standard
temperature. Assuming constant pressure, what
volume will the gas occupy if the temperature is
doubled?
(A)
(B)
(C)
(D)
(E)
25L
50L
100L
200L
2500L
101
All of the following statements underlie the kinetic
molecular theory of gases EXCEPT:
(A)
(B)
(C)
(D)
(E)
Gas molecules have no intermolecular forces
Gas particles are in random motion
The collisions between gas particles are elastic
Gas particles have no volume
The average kinetic energy is proportional to the
temperature (oC) of the gas
102
A 600-milliliter container holds 2 moles of O2(g), 3
moles of H2(g), and 1 mole of He(g). Total pressure
within the container is 760 torr. What is the partial
pressure of O2?
(A)
(B)
(C)
(D)
(E)
127 torr
253 torr
380 torr
507 torr
760 torr
103
Which of the gases below has the greatest average
kinetic energy at 25oC and 1 atm?
(A)
(B)
(C)
(D)
(E)
Ne
Ar
CO
CO2
All these gases would have the same average
kinetic energy under these conditions
104
If one mole of a gas originally at STP is placed in a
container where the pressure is doubled and the
temperature in K is tripled, what is the new volume in
L?
(A)
(B)
(C)
(D)
(E)
2.2
5.6
7.5
11.2
33.6
105
An ideal gas has a volume of 10 liters at 20oC and a
pressure of 750 mmHg. Which of the following
expressions is needed to determine the volume of the
same amount of gas at STP?
(A) 10 ´
(B) 10 ´
750 0
´ ´L
760 20
750 293
´
´L
760 273
760 0
(C) 10 ´
´ ´L
750 20
760 273
(D) 10 ´
´
´L
750 293
(E) 10 ´
750 273
´
´L
760 293
106
An ideal gas in a closed inflexible container has a
pressure of 6 atmospheres and a temperature of
27oC. What will be the new pressure of the gas if the
temperature is decreased to -73oC?
(A)
(B)
(C)
(D)
(E)
2 atm
3 atm
4 atm
8 atm
9 atm
107
Equal molar quantities of hydrogen gas and oxygen
gas are present in a closed container in a constant
temperature. Which of the following quantities will
be the same for the two gases?
I. Partial pressure
II. Average kinetic energy
III. Average molecular velocity
(A)
(B)
(C)
(D)
(E)
I only
I and II only
I and III only
II and III only
I, II, and III
108
Questions 1-3 pertain to the following situation.
A closed 5-liter vessel contains a sample of neon gas.
The temperature inside the container is 25oC, and the
pressure is 1.5 atmospheres. (The gas constant, R, is
equal to 0.08 L-atm/mol-K.)
1. Which of the following expressions is equal to the
molar quantity of gas in the sample?
(1.5)(5.0)
(A)
moles
(0.08)(25)
(0.08)(298)
(D)
moles
(1.5)(5.0)
(0.08)(25)
moles
(1.5)(5.0)
(1.5)(5.0)
(E)
moles
(0.08)(298)
(B)
(1.5)(25)
(C)
moles
(0.08)(5.0)
109
2. If the neon gas in the vessel is replaced with an
equal molar quantity of helium gas, which of the
following properties of the gas in the container will be
changed?
I. Pressure
II. Temperature
III. Density
(A)
(B)
(C)
(D)
(E)
I only
I and II only
III only
I and II only
II and III only
110
3. The volume of the vessel was gradually changed
while temperature was held constant until the
pressure was measure at 1.6 atmospheres. Which of
the following expressions is equal to the new
volume?
1.5
liters
1.6
1.6
(B) 5.0 ´
liters
1.5
(A) 5.0 ´
(C) 25´
1.5
liters
1.6
1.6
(D) 0.08´
liters
1.5
1.5
(E) 0.08´
liters
1.6
111
According to the ideal gas law, what is the
approximate volume that will be occupied by 0.5
mole of an ideal gas at 30oC and 3 atm pressure (gas
constant R = 0.0821 Latm/molK)?
(A)
(B)
(C)
(D)
(E)
Less than 1 L
5L
10 L
15 L
More than 20 L
112
A liter of hydrogen is at 5.0°C temperature and under
640. torr pressure. If the temperature were raised to
60.0°C and the pressure decreased to 320. torr, how
would the liter volume be modified?
(A) 1L ´
5.0 640
´
60. 32
(B) 1L ´
60. 320.
´
5.0 640.
278. 640.
(C) 1L ´
´
333 320.
333. 640.
(D) 1L ´
´
278. 320.
(E) 1L ´
333. 320.
´
278. 640.
113
Standard conditions (STP) are
(A)
(B)
(C)
(D)
(E)
0°C and 2 atm
32°F and 76 torr
273 K and 760 mm Hg
4°C and 7.6 cm Hg
0 K and 760 mm Hg
114
What is the boiling point of water at the top of Pikes
Peak?
(A) It is 100°C.
(B) It is > 100°C since the pressure is less than at
ground level.
(C) It is < 100°C since the pressure is less than at
ground level.
(D) It is > 100°C since the pressure is greater than at
ground level.
(E) It is < 100°C since the pressure is greater than at
ground level.
115
Graham’s Law refers to
(A)
(B)
(C)
(D)
Boiling points of gases
Gaseous diffusion
Gas compression problems
Volume changes of gases when the temperature
changes
116
When 200 milliliters of a gas at constant pressure is
heated, its volume
(A) Increases
(B) Decreases
(C) Remains unchanged
117
When 200 milliliters of a gas at constant pressure is
heated from 0°C to 100°C, the volume must be
multiplied by
(A)
(B)
(C)
(D)
0/100
100/0
273/373
373/273
118
At 5.00 atmospheres pressure and 70°C how many
moles are present in 1.50 liters of O2 gas?
(A)
(B)
(C)
(D)
0.036
0.266
0.536
0.103
119