UNIT 9 NOTES- CHEM H- GAS LAWS I
I.
Kinetic Molecular Theory(KMT)
In order to explain the forces between particles and the energy of particles,
scientists use a Model called the Kinetic Molecular Theory. A model is an
understandable representation of a system that cannot be easily understood.
The KMT only describes gases that are considered to be IDEAL
An Ideal Gas” …..
0) … does NOT truly exist. Many REAL gases behave nearly ideal if
pressure is not too high, and temperature is not too low. (These
conditions bring molecules closer together)
1. … Is a form of matter composed of very tiny particles (molecules or
atoms) that have mass. (Ex. An inflated beach ball weighs more than a
flat beach ball.)
The number of atoms in a gas particle does NOT affect the
physical behavior of the gas. (CH4 acts the same as He)
2. ….has a lot of space between gas particles which make them easily
compressible. The particles are so small compared to the distance
between them, so their volumes are considered to be ZERO.
3. …has molecules that are separated by vast spaces, and therefore have
no attractive or repulsive Intermolecular forces among them.
4. …has particles that are always in continual random motion. This is
why they diffuse quickly.
ex. Perfume molecules
5. has molecules whose average kinetic Energy (Energy of Motion)
remains constant after they collide. No energy loss occurs. Collisions
whose energy remain constant (no slowing down) are referred to as
“Elastic collisions” . The Kinetic energy*(KE) of a particle can be
described mathematically as …
KE = 1/2 m v2
, where m = mass, and v = velocity
The average kinetic energy of a gas depends upon the temperature of
the gas. The higher the temperature; the higher the kinetic energy.
II
III.
Characteristic Properties of Gases
The properties of gases come about from the fact that gas particles are far apart
from each other. Gases….
1. Gases have Mass.
2. Gases fill their container.
3. can be compressed or further expanded . (draw Pict)
4. exert pressure by colliding with objects
Pressure = FORCE
AREA
5. Have low density. Remember… D = M/V
6 undergo diffusion, the spontaneous spreading out of a gas in order to
occupy a space
A Closer Look at Pressure
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Gas Pressure results from billions of molecular collisions hitting the walls of a
container. The more collisions, the more pressure…less collisions produce less
pressure.
a. Ways to control pressure.
1. Increase the number of molecules over the same area(or volume)
yields more collisions
draw
2 Decrease the size of the container increases the number of collisions.
draw
3. Raising the temperature increases molecular motion (Kinetic Energy)
producing more collisions and more forceful collisions.
draw
B. Measuring Atmospheric Pressure- The BAROMETER
Vacuum in this space
Height of Hg in mm = Air Pressure
AIR
Hg
C. Units to measure Pressure
The average yearly air pressure at sea level would be:
760 Torr = 760 mm Hg = 1 Atmosphere (ATM) = 101.3 kilopascal (kPa)
(All values here are referred to as “STANDARD PRESSURE”)(SP)
D. Dalton’s law of Partial Pressure
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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John Dalton found that in a mixture of gases , each gas exerts pressure
independently of the other gases present. Dalton’s Law of Partial Pressures states that
the total pressure of a mixture of gases is equal to the sum of the pressures of all the gases
in the mixture. The portion of the total pressure contributed by a single gas is called its
partial pressure.
Ptotal = P1 + P2 +P3 +P4 + ….
Sample #1
A mixture of 2 moles Ne and 3 moles O2 have a combined pressure of
2.00 atmospheres. What is the Partial pressure of each gas ?
Sample #2
A Mixture of O2, CO2, and N2 has a total pressure of 0.97 ATM. What is the partial
pressure of O2, if the partial pressure of CO2 is 0.70 ATM and the partial pressure of N2 is
0.12 ATM ?
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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E. Temperature
The average kinetic energy of a gas depends upon the temperature of the gas, so this
means that “Temperature” reflects average kinetic energy of a gas. As fast moving
molecules bombard the thermometer bulb, energy is transferred to the bulb and hence to
the Mercury/alcohol in the thermometer. As a result, the molecules of alcohol(Hg) move
faster and expand through the capillary creating an increase in the temperature value on
the thermometer.
The Fahrenheit scale is used everyday but not for scientific purposes. The
Celsius Scale (oC) Based on the freezing and boiling points of water. The Kelvin
Temperature scale is a reflection of average kinetic energy of molecules. 0 K means that
there is no energy remaining in the molecule(or atom). This temperature is also known as
ABSOLUTE ZERO. At 0 K all molecular movement ceases.
__212 oF _____________100 oC ______________373K
___32 oF______________ 0 oC _______________273K
___-4500F _____________- 273.150C ___________ 0 K
To Convert
0
C to Kelvin (K)
K = Celsius + 273(.15)
The value of 273 K or 00C is also known as STANDARD TEMPERATURE (ST)
STP is STANDARD TEMPERATURE AND PRESSURE
The Gas Laws
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Boyles Law- At a constant temperature, the volume of a gas varies inversely with the
pressure. Mathematically it is expressed as P1V1 = P2V2 where the “ones” represent the
initial conditions, and the “twos” represent the final conditions.
Piston
piston pushed down
V1= 4.0L
P1 = 210kPa
V2= 2.0L
P2 = ?
initial condition
draw molecules
final condition
Sample #2A Sample of helium in a balloon is compressed from 4.0 Liters (L) to 2.0 L .
What is the new pressure if the original pressure was 210 kPa ?
NOTE: if temperature is not mentioned, it is remaining at some constant value.
V 1= 4.0L
P1V1 = P2V2
V2 = 2.0L
210 kPa (4.0L) = P2 (2.0 L)
P1 = 210 kPa
P2 = 420 kPa
P2 = ?
T1 & T2 = constant
Charles Law- At a constant pressure, the volume of a gas varies directly with the
KELVIN temperature. Mathematically it is expressed as V1 = V2
T1
T2
Sample #3A Sample of 4.0 L helium at 40.0 0C has its volume increase to 8.0 L under
constant pressure . What is the new Temperature in Celsius ?
NOTE : All temperatures must be expressed in Kelvins
K = C + 273
K = 40.0 + 273 = 313 K
V 1= 4.0L
V2 = 8.0L
T1 = 40 C = 313K
T2 = ?
P1 & P2 = constant
V1 = V2
T1
T2
4.0 L = 8.0 L
313K
T2
T2 = 626K
This Kelvin temperature is in need of being changed back to Celsius as prescribed by the
question
0
K = 0C + 273
so
626K = 0C +273
C = 3530
Charles Observed that Gas volumes increase by 1/273 for each degree the temperature
is raised from Zero Celsius at constant pressure
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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1.0 liter balloon
at 00 C
Volume increases
273/273 (or 1liter)
when temp goes to
273 0C
2.0L Balloon
Gay-Lussac’s Law- At a constant Volume, the Pressure of a gas varies directly with
the KELVIN temperature. Mathematically it is expressed as
P1 = P2
T1 T2
Sample #4The Pressure of propane gas in a barbecue tank (solid metal and constant
volume) is 3.20 Atm. At 22.0 0C . If the temperature rises to 60.0 0C , what will be the
pressure of the gas in the tank ?
NOTE : All temperatures must be expressed in Kelvins
K = C + 273
K = 22.0 + 273 = 295 K
K = 60.0 + 273 = 333 K
P 1= 3.20 Atm.
P2 = ?
T1 = 22.0 C = 295K
T2 = 60.0 C = 333K
P1 = P2
T1
T2
3.20 Atm = P2
295K
333K
P2 = 3.61 Atm
The Combined Gas Law- Boyle’s, Charles’s, and Gay-Lussac’s laws can be combined
into a single law when all three variable (PVT) are changed simultaneously. The
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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variables continue to have the same relationships to each other as they have in the three
gas laws already discussed. Mathematically
P1V1 = P2V2
T1
T2
Sample #5A Sample of 2.00L helium at 30.0 0C and 110 kPa fills a flexible container.
What is the new volume of the gas if the pressure increases to 440 kPa and the
temperature is raised to 80.0 0C ?
NOTE : All temperatures must be expressed in Kelvins
K = C + 273
K = 30.0 + 273 = 303 K
K = 80.0 + 273 = 353 K
P1V1 = P2V2
T1
T2
V1 = 2.00L
V2 = ?
T1 = 30 C = 303K
T2 80 C = 353K
P1 = 110 kPa
P2 = 440 kPa
110 kPa ( 2.00L ) =
303K
440 kPa (V2)
353K
V2 = 0.58 L
Worksheet MM H Chem
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Boyles, Charles, Gay-Lussac’s, Combined Gas Law Problems
1. Some oxygen occupies 150. ml when the pressure is 720. mm Hg. How many ml will
it occupy when the pressure is 750. mm Hg?
2. A nitrogen sample collected when the pressure is 800. torr has a volume of 190. ml.
What will be the volume at standard pressure?
3. Some hydrogen has a volume of 300. ml at a pressure of 740. mm. How many ml will
it occupy at 700. mm?
4. A sample of helium has a volume of 200. ml at 73.0 cm pressure. What pressure is
needed to reduce the volume to 50.0 ml?
5. Convert the following temperatures to Kelvin:
a) 25 C b) 70 C c) -18 C d) -253 C
6. Given 100. ml of hydrogen gas collected at 27.0 C, how many ml will it occupy at 42.0
C?
7. A sample of argon has a volume of 155 ml at a temperature of 37.0 C. At what celcius
temperature will the volume be 125 ml?
8. An oxygen sample occupies 80.0 ml at -33.0 C. What will be its volume at 33.0 C?
9. Some methane occupies 58.0 L at 17.0 C. What will be the volume at standard
temperature?
10. The gas left in an aerosol can is at a pressure of 1.00 atm at 27.0 C. If this can is
thrown into a fire, what will the internal pressure be when the temperature reaches
927 C?
11. A gas has a pressure of 75.0 mm Hg at 1200. K What will be the pressure at
350. K?
12. The gas in a container has a pressure of 2.65 atm at 80.0 C. What will be the pressure
if the temperature is lowered to -60.0 C?
13. A mass of O2 occupies 5.00 L at a pressure of 98.6 kPa. What is the volume at
standard pressure?
14. Given the volume of a gas is 200. ml at 800. torr, calculate the volume at 765 torr.
15. A mass of neon occupies 200. ml at 100.5 C. What is the volume at 0 C?
16. What volume will 10.0 cc of He measured at 12.0 C occupy at 36.0 C?
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Combined Gas Law Problems
17. A gas has a volume of 95.0 ml at a pressure of 710. torr and a temperature of
77.0 C. What will be the volume at STP?
18. What volume will 70.0 ml of N2 measured at 18.0 C and 104 kPa occupy at STP?
19. A mass of a gas occupies 10.0 ml when measured at 50.0 C and a pressure of
735 mm Hg. What pressure must be applied to make the gas volume 75.0 ml at a
temperature of 23.0 C?
20. At what temperature is a container of methane, 2.60 L and 1.40 atm if it is converted
to STP and then occupies 17.5 L?
21. Convert to standard conditions: 380. ml of Ar at 30.0 C and 107.7 kPa.
22. A sample of ethane is collected when the temperature is 27.0 C and the pressure is
80.0 cm. It has a volume of 300. ml. What will be the volume at -3 C and 75.0 cm?
23. A gas has a volume of 95.0 ml at a pressure of 700.0 torr and a temperature of
77.0 C. What volume will the gas occupy at STP?
24. What volume will 40.0 ml of nitrogen dioxide measured at 15 C and 780. torr occupy
at STP?
25. A mass of gas occupies 10.0 ml when measured at 50.0 C and 97.3 kPa. What
pressure must be applied to make the gas volume 75.0 ml at a temperature of 23 C?
26. Given 20.0 L of ammonia at 50 C and 760. torr What is the volume at 30 C and
800 torr?
27. A 2 liter helium balloon at 27oC is heated to a temperature of 100oC and a pressure
of 12,000 torrs. What was the initial pressure ?
Worksheet NN H Chem
Kinetic Molecular Theory
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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1. The odor coming from an open bottle of perfume several feet away shows that the molecules from the
perfume are in ______________ ______________ .
2. The impacts of gas molecules on the sides of a container cause _______________ .
3. As the temperature of a gas in a closed container rises, the molecules move faster causing the pressure to
_______________ .
4. When the atmospheric pressure on the surface of a liquid decreases the boiling point
____________________ .
5. Temperature is an indication of a molecules average _____________ ____________ .
6. When a gas is warmed (pressure unchanged) , its volume will _______________ .
7. If the volume of a gas in line 6 does not change, the pressure will ______________ .
8. Since the volume of a given weight of gas varies with its ___________________ and
_________________ , volumes of gases can be compared only under the same conditions.
9. For convenience in making in making comparisons, gas volumes are usually expressed at a temperature
of _________ ˚C and a pressure of ________ mm Hg.
These are called _______________ conditions (STP).
10. When the pressure on a given weight of a gas is doubled, (temp. unchanged) the volume of the gas
becomes _______________ as great.
11. Gas measured at 0˚C decreases 1/273 of its volume each time its temperature falls 1˚C (constant
pressure) and increases 1/273 of its volume each time its temperature rises 1˚C. This means that 273 ml of a
gas at 0˚C decreases ________ ml in volume at
-1˚C and becomes ________ ml.
12. The volume of a gas in line 11 becomes ________ ml at -10˚C, ________ ml at
-50˚C, and _______ at -100˚C. If this same rate of change continued to very low temperatures, the volume
of the gas (theoretically) would become zero at ________ ˚C.
13. When the absolute temperature of a gas is doubled (pressure unchanged) , the volume of the gas
becomes _______________ as great.
Collection of Gases
Gases can be collected using an assortment of instruments , the most common being the Eudiometer and
Manometer. They are pictured below:
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Gas Collected
Air Pressure
Gas Collected
Air Pressure
Hg
Hg
Eudiometer (tube)
Manometer
Both instruments are filled with Mercury (sometimes water) and can used to determine the gas pressure ,
given the Atmospheric Pressure (barometer reading) and the height difference of Hg in the instrument.
Eudiometer For the eudiometer, the level in the tube (eudiometer) is compared to the level in the tub.
Let’s suppose that the Barometric Pressure for the day is STANDARD (760 torr or mmHg) Noticed the
height differnce of the Mercury in each diagram A, B, and C
Gas
collected
Gas
collected
Gas
Collected
200mmHg
Air Pressure
Air Pressure
Air Pressure
50 mm Hg
Pgas
A
=P
B
air
Pgas
<P
air
C
Pgas >P
air
Eudiometer A - Notice that the Hg level in the tube (eudiometer) is at the same height as the level in the
tub. Since the collected gas is pushing down on the Mercury in the eudiometer as the Atmosphere is
pushing down on the Mercury in the tub, this means that the Pressure of the Atmosphere(Barometric
pressure) is the same as the gas collected in the eudiometer. So Gas Pressure = 760 mm Hg
Draw see-saw example:
Eudiometer B - Notice that the Hg level in the tube (eudiometer) is higher than the level in the tub.
Since the collected gas is pushing down on the Mercury in the eudiometer less than the Atmosphere is
pushing down on the Mercury in the tub, this means that the Pressure of the Atmosphere(Barometric
pressure) is greater than the gas collected in the eudiometer. So gas pressure = 760 - 200 = 560 mm Hg
Draw see-saw example
Eudiometer C - Notice that the Hg level in the tube (eudiometer) is lower than the level in the tub.
Since the collected gas is pushing down on the Mercury in the eudiometer more than the Atmosphere is
pushing down on the Mercury in the tub, this means that the Pressure of the Atmosphere(Barometric
pressure) is less than as the gas collected in the eudiometer. So gas pressure = 760 + 50 = 810 mm Hg
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Manometer For the Manometer, the Hg level on the “GAS side of the manometer is compared to the Hg
level of the open-ended side of in the “U- tube”. Let’s suppose that the Barometric Pressure for the day is
790 torr or mmHg) Noticed the height difference of the Mercury on each end of the manometer.
P-air = 790 mm
GAS
100 mm Hg
Notice the Open-ended Hg level is Higher than the Gas level in the manometer. This would represent the
lesser pressure. The gas Pressure would therefore be 790 + 100 = 890 mm Hg
Try These: determine the pressure of the gas in these diagrams
350 mm
Pair = 810 mm Hg
Pair = 680mm Hg
Pair = 727mm
25 mm
A1 = 460
B1= 705
C1= 727
Sample PROBLEM #6
A 38.5 ml sample of Hydrogen gas (H2) was collected in a eudiometer by displacement of Mercury.
The Mercury level inside the eudiometer was 28.0 mm higher than outside. The temperature of the gas was
23 0C and the barometric pressure was 733 mm Hg Convert the volume of Hydrogen to STP.
1. First list the variables for the gas collected (H2)
V1= 38.5 ml
V2= ?
P 1=
P2= 760 mm Hg
T1= 23 C = 296K
T2= O C = 273 K
Notice there is NO P1 variable . …733 mm Hg is not the Hydrogen pressure but the Air pressure!
P-barometric = 733 Hg
Draw the eudiometer based on the description, find the GAS pressure(H 2)P1 , Solve for V2 (answer = 33ml)
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Worksheet OO Gas/Hg Eudiometers/ Manometers
H Chem
NAME____________________________________
I. Complete each problem below being sure to construct the eudiometer/manometer. Show the equation
used.
1 59.0 ml of oxygen is collected by mercury displacement at a temperature of 30.0 C and a pressure of
725 mm Hg. The level inside the eudiometer is 13.0 mm higher than the level outside. What is the volume
at STP?
2. Carbon dioxide collected by displacement of Hg in an open end manometer occupies 65 ml. The Hg
level inside the(cylinder) is 15mm lower than the open ended side. The temperature is 18oC and the
barometer reads 754mm Hg. Convert the volume of CO2 to STP.
3. Some nitrogen is collected by Hg displacement in a eudiometer. Gas volume is 42.3 ml, Hg levels
inside and outside the tube are the same; temperature is 25oC, barometer reads 738 mmHg. Convert the
volume of the nitrogen to STP.
4. A volume of 34.7 ml of O2 is collected by mercury displacement using a manometer. The Hg level on
the flask side is 125 mm higher than the open-ended side. Temperature is 23oC, barometer reading is 715
mm Hg. Convert the volume of oxygen to STP.
5 . Carbon dioxide is collected by mercury displacement. The level inside is 15 mm lower than outside. It
occupies 65.0 ml at 18 C and 754 mm Hg. Convert to STP.
6. The volume of ammonia in a eudiometer is 43.0 ml The mercury level outside is
33 mm lower than inside. The barometer reads 740. torr. The temperature is 21 C. What will the volume be
at STP?
7. A volume of Kr in a eudiometer is 37.0 ml. The Hg level inside is 25 mm higher than outside. The
baromettric pressure is742 mm Hg. The temperature is 24 C. What will be the volume at 85 C and a
pressure of 812 mm Hg?
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Water Eudiometers
Although water is not toxic like Mercury it presents problems when trying to collect a gas sample. Water
itself becomes a vapor through evaporation at all temperatures, the higher the temperature the more water
vapor formed (See the water vapor pressure table). The pressure of water vapor is expressed in mm Hg just
like all other gases.
Lets take a look at Nitrogen collected by water displacement. If Nitrogen gas is collected on a day when
the Barometric pressure is 750 mm Hg and the Temperature is 25 C. The water level inside the eudiometer
is 136 mm higher than the level in the tub. What is the pressure of the “dry” nitrogen gas ?
1. First draw the eudiometer and label all parts.
N2 gas
Notice the height of the liquid in the tube is of mm water, not Hg
We must take the height of the water In mm and convert it into “
Mercury terms or language”.
Since Mercury is 13.6 times more dense than water, it would only be
pushed 1/13.6 the height of a water column. We divide
Water height in mm = Hg height
13.6
air pressure = 750mmHg
136 mm H20 = 10 mm Hg
13.6
H2O vapor
136 mm H20
H2O
We can now solve for the Total Pressure in eudiometer:
750 - 10 = 740 mm Hg
This is considered toi be the pressure of the Nitrogen and water vapor. Since we only need the pressure of
the Nitrogen gas, we have to use :Dalton’s Law of Partial Pressure” to solve for N 2 pressure
Ptotal =
`
P N2
+
P
H20
740.0 mm = P N2 + 23.8 mm Hg
P N2 = 716.2 mm Hg = P1
This pressure of nitrogen gas would then be used in either a combined gas law, Boyle’s, or GayLussac problem as the Initial Presssure
Sample problem #7
155 ml Oxygen gas is collected in a eudiometer by water displacement when the temperature is 34 C. The
water level inside the eudiometer is 67.0 mm higher than outside. The Barometer reads 741 mm Hg.
Convert the volume of dry oxygen to STP
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Temperature
oC
Water Vapor
Pressure kPa
Temperatur
e oC
Water Vapor
Pressure kPa
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
0.61129
0.65716
0.70605
0.75813
0.81359
0.87260
0.93537
1.00210
1.07300
1.14820
1.22810
1.31290
1.40270
1.49790
1.59880
1.70560
1.81850
1.93800
2.06440
2.19780
2.33880
2.48770
2.64470
2.81040
2.98500
3.16900
3.36290
3.56700
3.78180
4.00780
4.24550
4.49530
4.75780
5.03350
5.32290
5.62670
5.94530
6.27950
6.63980
6.99690
7.38140
7.78400
8.20540
8.64630
9.10750
9.58950
10.0940
10.6200
11.1710
11.7450
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
12.344
12.97
13.623
14.303
15.012
15.752
16.522
17.324
18.159
19.028
19.932
20.873
21.851
22.868
23.925
25.022
26.163
27.347
28.576
29.852
31.176
32.549
33.972
35.448
36.978
38.563
40.205
41.905
43.665
45.487
47.373
49.324
51.342
53.428
55.585
57.815
60.119
62.499
64.958
67.496
70.117
72.823
75.614
78.494
81.465
84.529
87.688
90.945
94.301
97.759
101.325
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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WORKSHEET PP
H Chem
NAME------------------------------------
1. A gas was collected by water displacement at a temperature of 32 C and a pressure of 99.6 kPa. It’s
volume is 38.2 ml. What is the volume of the dry gas at STP?
2. Some oxygen, 34.7 ml, is collected by water displacement at a temperature of 23 C and a pressure of 715
torr. Convert to STP.
3. Some nitrogen is collected by water displacement. The volume is 42.3 ml at 25 C and 98.4 kPa. Convert
to STP.
4. The volume of SO2 collected by water displacement at 18.0 C and 1500. mm Hg is 5.00 L. What is the
volume at 35.0 C and standard pressure?
5. 50.0 ml of He gas is collected by water displacement at 28.0 C The Water level inside the eudiometer
is 54 mm lower than in the tub. Convert the volume to STP if the Barometer reading that day is 742.0 mm
Hg
6. The air pressure is 705 mm Hg when 89.0 ml of Ne is collected over water at 13 C The water level
inside the eudiometer is 200 mm higher than outside. What is the new volume at 2.00 Atm. and 500 oC ?
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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Review Gas laws The test is very near, answers better be very clear.
1. What volume will 50.0 ml of a gas at 350. torr occupy if the pressure is increased to
700. torr?
2. What volume will 240. ml of a gas occupy if its temp is raised from 27 C to 127 C?
3. What will the volume be if 42.0 ml of a gas are changed from a pressure of 720 torr
and 27 C to 240 torr and -123 C?
4. What pressure is required to convert 200.0 ml of a gas at STP to 400.0 ml without any
temp change?
5. 3.40 L of oxygen gas were collected at 37 C and 40 torr. At 200.0 torr the volume
became 6.80 L. What is the new Celsius temp. for the gas?
6. 35 ml of hydrogen was collected in a eudiometer over mercury. The mercury level
inside the tube is 40 mm higher than outside. The temp is 25 C and the BP is 740 mm.
What volume would the H2 occupy at STP?
7. 60.0 ml of gas is collected over Hg and the level inside the tube is 25 mm lower than
outside. Temp = 20 C, BP = 715 mm Correct the volume to STP.
8. A gas measuring tube contains 25.0 ml of air. The gas was collected over water at 20
C. The water level was 68.0 mm higher inside with the atmospheric pressure = to 740.0
mm. Calculate the volume of the dry air at STP.
9. 45.0 ml of nitrogen is collected over water at a temp of 23.0 C. The water levels are
the same inside and outside, BP = 732.0 mm, What is the volume of the dry gas at STP?
10. a) State the 3 assumptions of KMT
b) List 5 characteristics of gases
Mr Treuer Chem H Notes 2012-13 Unit 9 Gas Laws I
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