Unit 9 Student Notes - Gas Laws
General Chemistry
KINETIC – MOLECULAR THEORY OF GASES
The kinetic molecular theory is based on the idea that particles of matter
are in _________________________________________.
1.
2.
3.
4.
5.
These postulates describe ________ gases. ________ gases act like ideal gases at _________________.
However at _________________ or ___________________, the behavior of real gases is significantly
different than ideal gases.
DEFINITIONS,VARIABLES, AND THEIR UNITS
Gas:
Kinetic Energy:
Pressure:
Partial Pressure:
Temperature:
STP:
The state of a gas can be described by four variables:
Quantity
(symbol)
Units
(symbol)
Page 1 of 6
Unit 9 Student Notes - Gas Laws
General Chemistry
Conversions:
*The temperature MUST be in KELVIN UNITS for any calculation in this unit!
Remember: __________________________________________
Example:
*It doesn’t matter what unit Pressure and Volume are in, as long as you use the
________________ within a single calculation.
Remember: __________________________________________
Examples:
Combined Gas Law:
Example Calculation:
What would be the volume in liters of an 8.90
liter sample of gas at 100.oC and 113 kPa if conditions were changed to STP?
DON’T FORGET: The term ____ stands for Standard Temperature and
Pressure. Mathematically, this means ___________________ (or 760 mm Hg or 101.3 kPa) and
_________ (or 273 K).
Boyle’s Law:
Real Life Application:
Example Calculation: 1.00 L of a gas at standard temperature and
pressure is compressed to 473 mL. What is the new pressure of the gas?
Page 2 of 6
Unit 9 Student Notes - Gas Laws
General Chemistry
Charles’s Law:
Real Life Application:
Example Calculation: A man heats a balloon in the oven.
If the balloon
initially has a volume of 0.4 liters and a temperature of 20 C, what will the
volume of the balloon be after he heats it to a temperature of 250 0C?
0
Gay-Lussac’s Law:
Real Life Application:
Example Calculation:
If the pressure on a gas in a rigid container
changes from 800. mmHg to 2.15 atm, and at the lower pressure, the
temperature is found to be 40.0°C, what was the final temperature in
Kelvin?
Avogadro’s Law:
Real Life Application:
Example Calculation: A 36.2 mole sample of carbon dioxide occupies a volume of 5.20 liters.
If
15.4 more liters are added, how many moles would you have if the pressure and temperature remains
constant?
Page 3 of 6
Unit 9 Student Notes - Gas Laws
General Chemistry
Dalton’s Law of Partial Pressure:
What if the units are not the same???
Ptotal = PA + PB + PC + …for however many gases you have!
Example Calculation:
There is a container which has oxygen, xenon and helium in it. Its total
pressure is known to be 972 mmHg. If the pressure of the helium is 0.458 atm and the pressure of the
oxygen is 74.1 kPa, what is the pressure of the Xenon in mmHg?
Dalton’s Law Over Water:
The gas
collected
includes the
desired gas
AND water
vapor… so…
Example Calculation:
50.0 ml of hydrogen collected over water and has a pressure of
850. mmHg at 27.0oC. What is the pressure of the dry gas at STP?
Vapor
Pressure
(torr)
Temperature
(°C)
Vapor
Pressure
(torr)
Temperature
(°C)
Vapor
Pressure
(torr)
Temperature
(°C)
Vapor
Pressure
(torr)
2.1
2.3
2.5
2.7
2.9
3.2
3.4
3.7
4.0
4.3
4.6
4.9
5.3
5.7
6.1
6.5
7.0
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
18.7
19.8
21.1
22.4
23.8
25.2
26.7
28.3
30.0
31.8
33.7
35.7
37.7
39.9
42.2
44.6
47.1
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
97.2
102.1
107.2
112.5
118.0
123.8
129.8
136.1
142.6
149.4
156.4
163.8
171.4
179.3
187.5
196.1
205.0
81
82
83
84
85
86
87
88
89
90
91
92
93
94
Page95
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96
97
369.7
384.9
400.6
416.8
433.6
450.9
468.7
487.1
506.1
525.8
546.1
567.0
588.6
610.9
633.9
657.6
682.1
Ptotal =
Pwater +
Pgas
Unit 9 Student Notes - Gas Laws
General Chemistry
(torr = mmHg)
Ideal Gas Law:
PV = nRT
P=
V=
n=
R=
T=
LmmHg
Latm
LkPa
R  0.0821 mol
or
62.4
or 8.314 mol
K
mol K
K
Example Calculation:
How many moles of oxygen must be put in a 0.500 L flask at 20.00C to have a
pressure in the flask of 1.77 atm?
Example Calculation:
If 1.17 grams of helium are put into a 500.0 ml container at 100C, what
would be the pressure of the container (in mmHg)?
Page 5 of 6
Unit 9 Student Notes - Gas Laws
General Chemistry
Gas Laws Intro
Combined Gas Law
12:10
8:09
Unit 9: Video 2
Unit 9: Video 1
(video 1, Gas Laws Intro on YouTube channel)
Boyle’s Law
(video 2, Combined Gas Law on YouTube channel)
Charles’s Law
4:22
Unit 9: Video 3
(video 4, Charles’s Law on YouTube channel)
(video 3, Boyle’s Law on YouTube channel)
Gay Lussac’s Law
4:07
Unit 9: Video 4
Avogadro’s Law
6:16
4:33
Unit 9: Video 6
Unit 9: Video 5
(video 5, Gay Lussac’s Law on YouTube channel)
(video 6, Avogadro’s Law on YouTube channel)
Dalton’s Law of Partial Pressure
8:19
Unit 9 : Video 7
(video 7, Dalton’s Law of Partial Pressure on
YouTube channel)
Ideal Gas Law 11:38
Unit 9: Video 8
(video 8, Ideal Gas Law on YouTube channel)
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