moczulski (ksm935) – H02: Gas Laws – mccord – (50960)
1
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printout
should
have
23
questions.
Multiplechoice questions may continue on
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before answering.
001
10.0points
A gas is enclosed in a 10.0 L tank at 1200
mm Hg pressure.
Which of the following is
a reasonable value for the pressure when the
gas is pumped into a 5.00 L vessel?
1.
24 mm Hg
2.
0.042 mm Hg
3.
600 mm Hg
4.
2400 mm Hg
correct
Explanation:
V
1
= 10.0 L
V
2
= 5.0 L
P
1
= 1200 mm Hg
Boyle’s law relates the volume and pressure
of a sample of gas:
P
1
V
1
=
P
2
V
2
P
2
=
P
1
V
1
V
2
=
(1200 mm Hg)(10
.
0 L)
5 L
= 2400 mm Hg
002
10.0points
A sample of gas in a closed container at a
temperature of 99
◦
C and a pressure of 8 atm
is heated to 306
◦
C. What pressure does the
gas exert at the higher temperature?
Correct answer: 12
.
4516 atm.
Explanation:
T
1
= 99
◦
C + 273 = 372 K
P
1
= 8 atm
T
2
= 306
◦
C + 273 = 579 K
P
2
= ?
Applying the GayLussac law,
P
1
T
1
=
P
2
T
2
P
2
=
P
1
T
2
T
1
=
(8 atm) (579 K)
372 K
= 12
.
4516 atm
003
10.0points
If I have 44.8 liters of nitrogen gas at standard
temperature and pressure, how much will it
weigh?
1.
56 u
2.
28 g
3.
28 kg
4.
44.8 g
5.
56 g
correct
Explanation:
P
= 1 atm
V
= 44
.
8 L
T
= 273 K
P V
=
n R T
n
=
P V
R T
n
=
(1 atm)(44
.
8 L)
(
0
.
08206
L
·
atm
K
·
mol
)
(273 K)
·
28 g
1 mol
= 55
.
9941 g
004
10.0points
At 80.0
◦
C and 12.0 Torr, the density of cam
phor vapor is 0
.
0829 g
·
L
−
1
.
What is the
molar mass of camphor?
1.
20
.
3 g
·
mol
−
1
2.
243 g
·
mol
−
1
3.
3490 g
·
mol
−
1
4.
152 g
·
mol
−
1
correct
5.
34
.
5 g
·
mol
−
1
Explanation:
T
= 80
◦
C + 273.15 K = 353.15 K
P
= (12 Torr)
1 atm
760 Torr
= 0
.
0157895 atm
ρ
= 0
.
0829 g/L
The ideal gas law is
P V
=
n R T
n
V
=
P
R T
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moczulski (ksm935) – H02: Gas Laws – mccord – (50960)
2
with unit of measure mol/L on each side.
Multiplying each by molar mass (MM) gives
n
V
·
MM =
P
R T
·
MM =
ρ ,
with units of g/L.
MM =
ρ R T
P
=
(0
.
0829 g
/
L)
(
0
.
08206
L
·
atm
mol
·
K
)
0
.
0157895 atm
×
(353
.
15 K)
= 152
.
152 g
/
mol
005
10.0points
What is the density of nitrogen gas at STP?
1.
2.50 g/L
2.
0.500 g/L
3.
4.00 g/L
4.
0.625 g/L
5.
1.25 g/L
correct
Explanation:
006(part1of3)10.0points
A chemist has synthesized a greenishyellow
gaseous compound that contains only chlorine
and oxygen and has a density of 7.71 g/L
at 36.0 degrees Celsius and 2188.8 mm Hg.
What is the molar mass of the compound?
1.
25.8 g/mol
2.
67.9 g/mol
correct
3.
109 g/mol
4.
86.9 g/mol
5.
51.5 g/mol
Explanation:
T
= 36
◦
C + 273 = 309 K
P
= 2188
.
8 mm Hg
atm
760 mm Hg
= 2
.
88 atm
P V
=
n R T
n
V
=
P
R T
=
(2
.
88 atm)
(309 K)(0
.
08206
L
·
atm
molK
)
= 0
.
1136
mol
L
MW =
7
.
71 g
/
L
0
.
1136
mol
L
= 67
.
87 g
/
mol
007(part2of3)10.0points
What is the molecular formula of the com
pound?
1.
ClO
4
2.
ClO
3
3.
ClO
4.
ClO
2
correct
5.
ClO
5
Explanation:
MW
ClO
2
= (35
.
5) + 2(16) = 67
.
5 g
/
mol
008(part3of3)10.0points
How many moles of this gaseous compound
are there in 15 L at STP?
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 gas particles

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