General Chemistry
Principles & Modern Applications
9th Edition
Petrucci/Harwood/Herring/Madura
Chapter 6
Gases
Dr. Travis D. Fridgen
Memorial University of Newfoundland
© 2007 Pearson Education
In which of the figures below is the pressure in the gas bulb greater
than atmospheric pressure?
1.
2.
3.
In which of the figures below is the pressure in the gas bulb greater
than atmospheric pressure?
1.
2.
3.
What is the pressure exerted by a 50 kg
ballet dancer standing on her toe (~2 cm2).
Assume g is ~10 m s-2.
(Note: atmospheric pressure is ~1x105 Pa
1. 0.025 Pa
2. 250 Pa
3. 2.5x104 Pa
4. 2.5x106 Pa
5. 2.5x108 Pa
Edgar Degas, Danseuses bleues, 1890
Musee d’Orsay, Paris
What is the pressure exerted by a 50 kg
ballet dancer standing on her toe (~2 cm2).
Assume g is ~10 m s-2.
(Note: atmospheric pressure is ~1x105 Pa
1. 0.025 Pa
2. 250 Pa
3. 2.5x104 Pa
4. 2.5x106 Pa
5. 2.5x108 Pa
Edgar Degas, Danseuses bleues, 1890
Musee d’Orsay, Paris
Boyle’s law as an equation is V × P = c, where c=constant
An expression for the final volume, V2, occupied
by a gas from the initial volume, V1, when the
pressure is changed from P1 to P2 at constant
temperature is,
1. V2 =
P2
P1V1
3. V2 =
P2
P1V1
2. V2 =
cP2
P1V1
4. V2 =
P1V1
P2
5. V2 =
P2 V1
P1
Boyle’s law as an equation is V × P = c, where c=constant
An expression for the final volume, V2, occupied
by a gas from the initial volume, V1, when the
pressure is changed from P1 to P2 at constant
temperature is,
1. V2 =
P2
P1V1
3. V2 =
P2
P1V1
2. V2 =
cP2
P1V1
4. V2 =
P1V1
P2
5. V2 =
P2 V1
P1
A 100 L vessel at 30 atm is attached
to another vessel and gas is allowed
to equilibrate between the two. The
pressure was then found to be 10
atm. Use Boyle’s Law to determine
the Volume of the second, oddly
shaped, container.
1. 50 L
2. 100 L
3. 200 L
V=?
P1=30 atm
100 L
4. 300 L
5. 400 L
P1=10 atm
100 L
A 100 L vessel at 30 atm is attached
to another vessel and gas is allowed
to equilibrate between the two. The
pressure was then found to be 10
atm. Use Boyle’s Law to determine
the Volume of the second, oddly
shaped, container.
1. 50 L
2. 100 L
3. 200 L
V=?
P1=30 atm
100 L
4. 300 L
5. 400 L
P1=10 atm
100 L
Charles’ law as an equation is
V
= c, where c=constant
T
An expression for the final volume, V2,
occupied by a gas from the initial volume, V1,
when the temperature is increased from T1 to
T2 at constant pressure is,
100
1. V2 =
T2
T1V1
3. V2 =
T2
T1V1
5. V2 =
cT2
2. V2 =
T1V1
TV
4. V2 = 1 1
T2
T2 V1
T1
Volume / mL
80
60
40
20
0
0
100
200
300
400
Temperature / K
500
600
Charles’ law as an equation is
V
= c, where c=constant
T
An expression for the final volume, V2,
occupied by a gas from the initial volume, V1,
when the temperature is increased from T1 to
T2 at constant pressure is,
100
1. V2 =
T2
T1V1
3. V2 =
T2
T1V1
5. V2 =
cT2
2. V2 =
T1V1
TV
4. V2 = 1 1
T2
T2 V1
T1
Volume / mL
80
60
40
20
0
0
100
200
300
400
Temperature / K
500
600
Without doing detailed calculations, which of the following gases has
the greatest density at STP?
1. O2
2. N2
3. Kr
4. CH4
5. C3H6
Without doing detailed calculations, which of the following gases has
the greatest density at STP?
1. O2
2. N2
3. Kr
4. CH4
5. C3H6
You take a 2.0 L volume of gas at 25 oC.
You double both the volume and the
temperature to 4.0 L and 50 oC, respectively.
The pressure of the gas…
1. Doubles
2 L
4 L
50 oC
2. Quadruples
3. Halves
25 oC
4. Remains the same
5. None of these answers
Caricature of Bunsen
by William B. Jensen
You take a 2.0 L volume of gas at 25 oC.
You double both the volume and the
temperature to 4.0 L and 50 oC, respectively.
The pressure of the gas…
1. Doubles
2 L
4 L
50 oC
2. Quadruples
3. Halves
25 oC
4. Remains the same
5. None of these answers
Caricature of Bunsen
by William B. Jensen
You take a 4.0 L volume of gas at 300 K. You
compress the gas to a 2.0 L volume and
simultaneously heat the vessel to 600 K. The
pressure of the gas…
4 L
1. Doubles
2 L
600 K
2. Quadruples
3. Halves
300 K
4. Remains the same
5. None of these answers
Caricature of Bunsen
by William B. Jensen
You take a 4.0 L volume of gas at 300 K. You
compress the gas to a 2.0 L volume and
simultaneously heat the vessel to 600 K. The
pressure of the gas…
4 L
1. Doubles
2 L
600 K
2. Quadruples
3. Halves
300 K
4. Remains the same
5. None of these answers
Caricature of Bunsen
by William B. Jensen
The contents of two 5 L containers,
one containing H2 and the other
containing He are combined as
depicted to the right. What is the
final Pressure of the 5.0 L vessel?
0.50 mol H2
P=2.4 atm
1.25 mol He
P=6.0 atm
0.50 mol H2
1.25 mol He
P=?
?????
1. 1.75 atm
2. 2.4 atm
3. 6.0 atm
4. 8.4 atm
5. 10.8 atm
5.0 L @ 20 oC
5.0 L @ 20 oC
5.0 L @ 20 oC
The contents of two 5 L containers,
one containing H2 and the other
containing He are combined as
depicted to the right. What is the
final Pressure of the 5.0 L vessel?
0.50 mol H2
P=2.4 atm
1.25 mol He
P=6.0 atm
0.50 mol H2
1.25 mol He
P=?
?????
1. 1.75 atm
2. 2.4 atm
3. 6.0 atm
4. 8.4 atm
5. 10.8 atm
5.0 L @ 20 oC
5.0 L @ 20 oC
5.0 L @ 20 oC
In the electrolysis of a sample of water 100 mL
of O2 was collected. What volume of H2 was
collected?
2H 2O(l)
→ 2H 2 (g) + O2 (g)
1. 20 mL
2. 50 mL
3. 100 mL
4. 150 mL
5. 200 mL
In the electrolysis of a sample of water 100 mL
of O2 was collected. What volume of H2 was
collected?
2H 2O(l)
→ 2H 2 (g) + O2 (g)
1. 20 mL
2. 50 mL
3. 100 mL
4. 150 mL
5. 200 mL
0.5 mol of water was decomposed in an
electrolysis experiment. What volume
each of H2 and O2 were collected at STP?
2H 2O(l)
→ 2H 2 (g) + O2 (g)
1. 22.4 L of each.
2. 11.2 L of each.
3. 11.2 L H2, 22.4 L of O2.
4. 22.4 L H2, 11.2 L of O2.
5. 22.4 L H2, 44.8 L of O2.
0.5 mol of water was decomposed in an
electrolysis experiment. What volume
each of H2 and O2 were collected at STP?
2H 2O(l)
→ 2H 2 (g) + O2 (g)
1. 22.4 L of each.
2. 11.2 L of each.
3. 11.2 L H2, 22.4 L of O2.
4. 22.4 L H2, 11.2 L of O2.
5. 22.4 L H2, 44.8 L of O2.
What volume of hydrogen at STP is required to
hydrogenate one mole of oleic acid
(C17H33COOH) to one mole of stearic acid
(C17H35COOH)?
1. 11.2 L
2. 22.4 L
3. 44.8 L
4. 56.0 L
5. 67.2 L
What volume of hydrogen at STP is required to
hydrogenate one mole of oleic acid
(C17H33COOH) to one mole of stearic acid
(C17H35COOH)?
1. 11.2 L
2. 22.4 L
3. 44.8 L
4. 56.0 L
5. 67.2 L
NaH and CaH2 react with water to produce
hydrogen gas according to the following
equation.
MH n + nH 2O
→
M(OH) n + nH 2
The molar masses of Na and Ca are,
22.99 and 40.08 g mol-1, respectively.
Which produces the most H2 per gram?
1. NaH
2. CaH2
3. Per gram, both produce the same.
NaH and CaH2 react with water to produce
hydrogen gas according to the following
equation.
MH n + nH 2O
→
M(OH) n + nH 2
The molar masses of Na and Ca are,
22.99 and 40.08 g mol-1, respectively.
Which produces the most H2 per gram?
1. NaH
2. CaH2
3. Per gram, both produce the same.
According to the kinetic molecular theory the root
mean square speed of ammonia, NH3, is 660 m
s-1 at 298 K. That means that 30 ms after taking
the top off a bottle of ammonium hydroxide a
person at the back of a room, 20 m away, will
experience the debilitating odour of ammonia
(choose the best response).
1. True
2. False
3. This is a flaw with the
kinetic molecular theory.
According to the kinetic molecular theory the root
mean square speed of ammonia, NH3, is 660 m
s-1 at 298 K. That means that 30 ms after taking
the top off a bottle of ammonium hydroxide a
person at the back of a room, 20 m away, will
experience the debilitating odour of ammonia
(choose the best response).
1. True
2. False
3. This is a flaw with the
kinetic molecular theory.
The normal economical cruising speed of
a Boeing 767 is 854 km h-1 (237 m s-1).
Xe (131.29 g mol-1) has about the same
root mean square speed at 298 K. Which
of the following gases would beat the
Boeing 767 in a race?
1. Cl2
4. Both 1 and 2.
2. Kr
5. All of these.
3. Br2
17
35
36
Cl
Br
Kr
35.4527
79.904
83.80
The normal economical cruising speed of
a Boeing 767 is 854 km h-1 (237 m s-1).
Xe (131.29 g mol-1) has about the same
root mean square speed at 298 K. Which
of the following gases would beat the
Boeing 767 in a race?
1. Cl2
4. Both 1 and 2.
2. Kr
5. All of these.
3. Br2
17
35
36
Cl
Br
Kr
35.4527
79.904
83.80
At 320 K and 16 atm, the molar volume of ammonia, NH3, is about 10%
less than that of an ideal gas. The best explanation for this observation is
1. The volume of an NH3 molecule is significant at this concentration.
2. The volume of an NH3 molecule is smaller than that of
an ideal gas.
3. At this temperature, a significant amount of NH3
decomposes to N2 and H2.
4. Intermolecular forces of attraction for NH3 become
significant at this temperature and pressure.
5. None of the above answers explains this strange observation.
At 320 K and 16 atm, the molar volume of ammonia, NH3, is about 10%
less than that of an ideal gas. The best explanation for this observation is
1. The volume of an NH3 molecule is significant at this concentration.
2. The volume of an NH3 molecule is smaller than that of
an ideal gas.
3. At this temperature, a significant amount of NH3
decomposes to N2 and H2.
4. Intermolecular forces of attraction for NH3 become
significant at this temperature and pressure.
5. None of the above answers explains this strange observation.
There are always attractive forces between a collection of atoms or molecules
which may not be negligible as suggested by the kinetic molecular theory.
The strength of these forces depend upon the nature of the atom or molecule.
If a mole of gas is at STP and there are very strong attractive intermolecular
forces between the gas particles the volume will be
1. 22.4 L
2. greater than 22.4 L
3. less than 22.4 L
3. none of these
atm P
There are always attractive forces between a collection of atoms or molecules
which may not be negligible as suggested by the kinetic molecular theory.
The strength of these forces depend upon the nature of the atom or molecule.
If a mole of gas is at STP and there are very strong attractive intermolecular
forces between the gas particles the volume will be
1. 22.4 L
2. greater than 22.4 L
3. less than 22.4 L
3. none of these
atm P
If you have a mole of a real gas in which there are substantial
intermolecular forces between the gas molecules in a 22.4 L
container at 273 K (standard temperature) will the pressure be
1. 1 atmosphere
2. greater than 1 atm
3. less than 1 atm
If you have a mole of a real gas in which there are substantial
intermolecular forces between the gas molecules in a 22.4 L
container at 273 K (standard temperature) will the pressure be
1. 1 atmosphere
2. greater than 1 atm
3. less than 1 atm
Neon is about
1. half
2. one quarter
3. twice
4. four times
as dense as argon?
Neon is about
1. half
2. one quarter
3. twice
4. four times
as dense as argon?
Which has the greatest mass?
1. 22.4 L of He at STP
2. 1 mole of N2 at STP
3. 2 moles of H2 at STP
4. 20 g of Ne
5. All have the same mass
Which has the greatest mass?
1. 22.4 L of He at STP
2. 1 mole of N2 at STP
3. 2 moles of H2 at STP
4. 20 g of Ne
5. All have the same mass
Bromine (Br2) and argon (Ar) gases have molar masses of 160 and 40 g
mol-1 respectively. 1.0 x 10-5 mol of argon effuses through a tiny hole in 1
hour. How long would it take for the same amount of bromine to effuse
through the same hole?
1. 4 hours
4. 20 minutes
2. 2 hours
5. 15 minutes
3. 30 minutes
Bromine (Br2) and argon (Ar) gases have molar masses of 160 and 40 g
mol-1 respectively. 1.0 x 10-5 mol of argon effuses through a tiny hole in 1
hour. How long would it take for the same amount of bromine to effuse
through the same hole?
1. 4 hours
4. 20 minutes
2. 2 hours
5. 15 minutes
3. 30 minutes
Oxygen (O2) and hydrogen (H2) gases have molar masses of 32.0 and 2.0
g mol-1 respectively. 2.00 x 10-2 mol of hydrogen effuses through a tiny
hole in 1 hour. How much oxygen effuses through the same hole in the
same amount of time?
1.
3.2 x 10-1 mol
2.
1.6 x 10-2 mol
3.
8.0 x 10-2 mol
4.
5.0 x 10-3 mol
5.
2.5 x 10-3 mol
Oxygen (O2) and hydrogen (H2) gases have molar masses of 32.0 and 2.0
g mol-1 respectively. 2.00 x 10-2 mol of hydrogen effuses through a tiny
hole in 1 hour. How much oxygen effuses through the same hole in the
same amount of time?
1.
3.2 x 10-1 mol
2.
1.6 x 10-2 mol
3.
8.0 x 10-2 mol
4.
5.0 x 10-3 mol
5.
2.5 x 10-3 mol