fernandez (jf23742) – Homework 7 – Brodbelt – (53765)
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Homework 7: Gases
001
10.0 points
The same number of grams of NH
3
and O
2
are placed in separate bulbs of equal vol
ume and temperature under conditions when
both gases behave ideally. Which statement
is true?
1.
The pressure in the NH
3
bulb is greater
than the pressure in the O
2
bulb.
correct
2.
The pressure in the O
2
bulb is greater
than the pressure in the NH
3
bulb.
3.
Both bulbs contain the same number of
moles of gas.
4.
The bulb containing O
2
contains more
molecules of gas.
5.
The pressures in the two bulbs are the
same.
Explanation:
The molecular weight of NH
3
is less than
that of O
2
, so in equal masses there are more
moles of NH
3
than of O
2
. At the same volume
and temperature, the larger number of moles
of NH
3
would exert a higher pressure.
002
10.0 points
How many molecules are in 1.00 liter of O
2
gas at 56
◦
C and 821 torr.
1.
32 molec
2.
2
.
24
×
10
23
molec
3.
1
.
83
×
10
25
molec
4.
2
.
41
×
10
22
molec
correct
5.
4
.
00
×
10

2
molec
Explanation:
V
= 1 L
T
= 56
◦
C + 273 = 329 K
P
= 821 torr
·
atm
760 torr
= 1
.
08 atm
Applying the ideal gas law equation,
P V
=
n R T
n
=
P V
R T
n
=
(1
.
08 atm) (1 L)
(
0
.
08206
L
·
atm
mol
·
K
)
(329 K)
·
6
.
02
×
10
23
molec
1 mol
= 2
.
41
×
10
22
molec
003
10.0 points
At STP, 6.0 grams of CO gas will occupy a
volume of
1.
3.5 liters.
2.
4.8 liters.
correct
3.
22.4 liters.
4.
5.6 liters.
5.
2.24 liters.
Explanation:
T
= 0
◦
C + 273 = 273 K
P
= 1 atm
n
= 6 g
·
mol
28 g
= 0
.
214 mol
Applying the ideal gas law,
P V
=
n R T
V
=
n R T
P
V
=
(0
.
214 mol)
(
0
.
08206
L
·
atm
mol
·
K
)
(273 K)
1 atm
= 4
.
79411 L
004
10.0 points
A flask contains 0.123 moles of an ideal gas
that occupies 781 mL. A second flask at the
same temperature contains 0.0712 moles of
the same gas.
The pressure is the same in
both flasks. What is the volume of the second
flask?
1.
452 mL
correct
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fernandez (jf23742) – Homework 7 – Brodbelt – (53765)
2
2.
89,180 mL
3.
1350 mL
4.
904 mL
5.
6.8 mL
Explanation:
n
1
= 0
.
123 mol
n
2
= 0
.
0712 mol
V
1
= 781 mL
Applying the ideal gas law equation,
P V
=
n R T
V
1
V
2
=
n
1
n
2
V
2
=
V
1
n
2
n
1
V
2
=
(781 mL) (0
.
0712 mol)
0
.
123 mol
= 452 mL
005
10.0 points
What is the volume of 0.500 moles of an ideal
gas at 273 K and 760 torr?
1.
11.2 liters
correct
2.
22.4 liters
3.
4.56 cubic fathoms
4.
380 ml
5.
2.24 liters
Explanation:
n
= 0
.
5 mol
R
= 0
.
08206
L
·
atm
mol
·
K
P
= 760 torr = 1 atm
T
= 273 K
P V
=
n R T
V
=
n R T
P
=
(0
.
5 mol)
(
0
.
08206
L
·
atm
mol
·
K
)
(273 K)
1 atm
= 11
.
2012 L
006
10.0 points
A 2.00 mole sample of gas is at a temperature
of 100.0
◦
C and occupies 3.00 liters. What is
its pressure?
1.
0.0500 atm
2.
5.50 atm
3.
20.4 atm
correct
4.
The correct answer is not given.
5.
0.180 atm
Explanation:
n
= 2 mol
T
= 100
◦
C + 273 = 373 K
V
= 3 L
Applying the ideal gas law equation,
P V
=
n R T
P
=
n R T
V
P
=
(2 mol)
(
0
.
08206
L
·
atm
mol
·
K
)
(373 K)
3 L
= 20
.
4 atm
007
10.0 points
How many moles of HCl gas are produced if
5.00 L of Cl
2
and excess H
2
are reacted at
STP?
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 Spring '09
 COWLEY
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