Gu, Phillip – Homework 7 – Due: Oct 31 2007, 11:00 pm – Inst: Brodbelt
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Brodbelt CH301
Homework 7
Due October 31, 2007 at 11:00 PM
001
(part 1 of 1) 10 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 pressures in the two bulbs are the
same.
2.
The pressure in the NH
3
bulb is greater
than the pressure in the O
2
bulb.
correct
3.
The pressure in the O
2
bulb is greater
than the pressure in the NH
3
bulb.
4.
Both bulbs contain the same number of
moles of gas.
5.
The bulb containing O
2
contains more
molecules of gas.
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
(part 1 of 1) 10 points
How many molecules are in 1.00 liter of O
2
gas at 56
◦
C and 821 torr.
1.
1
.
83
×
10
25
molec
2.
32 molec
3.
2
.
24
×
10
23
molec
4.
4
.
00
×
10

2
molec
5.
2
.
41
×
10
22
molec
correct
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
(part 1 of 1) 10 points
At STP, 6.0 grams of CO gas will occupy a
volume of
1.
22.4 liters.
2.
3.5 liters.
3.
2.24 liters.
4.
5.6 liters.
5.
4.8 liters.
correct
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
(part 1 of 1) 10 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
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Gu, Phillip – Homework 7 – Due: Oct 31 2007, 11:00 pm – Inst: Brodbelt
2
the same gas.
The pressure is the same in
both flasks. What is the volume of the second
flask?
1.
6.8 mL
2.
452 mL
correct
3.
89,180 mL
4.
1350 mL
5.
904 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
(part 1 of 1) 10 points
What is the volume of 0.500 moles of an ideal
gas at 273 K and 760 torr?
1.
4.56 cubic fathoms
2.
2.24 liters
3.
11.2 liters
correct
4.
22.4 liters
5.
380 ml
Explanation:
006
(part 1 of 1) 10 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.
The correct answer is not given.
3.
5.50 atm
4.
0.180 atm
5.
20.4 atm
correct
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
(part 1 of 1) 10 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 '07
 Fakhreddine/Lyon
 Chemistry, pH, mol

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