Chapter 11: Physical Properties of Gases
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Objectives
Describe how the kinetic-molecular theory of matter explains ideal gases
Differentiate between ideal and real gases
Describe temperature & pressure and convert units.
State the conditions of STP
Explain the relationship between volume, temperature and pressure of gases
Calculate the relationship of V, T, P using Boyle’s, Charles’, and Gay Lussac’s laws
Perform the calculations with the combined gas law
Calculate partial pressures from Dalton’s law.
A. Kinetic-Molecular Theory
of Ideal Gases
Particles in an ideal gas …
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are ______________________ relative to their size.
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have elastic collisions
(_______________________________________________).
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are in constant, random, rapid ___________________________.
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don’t ___________________________ each other.

have an avg. KE directly related to ____________________________.
B. Real Gases
Particles in a REAL gas…
have their own ____________________________
_________________________ each other
Gas behavior is most ideal…
at low ______________________
at high _____________________
in nonpolar _________________________ (He, Ne, H 2, N2, I2 etc.)
C. Characteristics of gases
•
Gases _____________________ any container.
– random motion, no attraction
•
Gases are ______________________ (like liquids).
– no attraction
•
Gases have very low ____________________________.
– no volume = lots of empty space
D. Temperature
•
Gases can be __________________________.
– no volume = lots of empty space
•
Gases undergo ____________________________________.
- Random motion
Always use absolute temperature
E. Pressure
___________________________
- Measures atmospheric pressure
____________________________
- Invented by
Key units at sea level
F. STP
G. Dalton’s Law of Partial
Pressures
STP means:
A gas is collected over water at a temp of 35.0°C when the
barometric pressure is 742.0 torr. What is the partial pressure
of the dry gas?
Law:
Given:
Work:
H. Boyle’s Law
The pressure and volume of a gas are ___________________ related
- at constant mass & temp
I. Charles’ Law
The volume and absolute temperature (K) of a gas are ________________ related
- at constant mass & pressure
J. Gay Lussac’s Law
The pressure and absolute temperature (K) of a gas are _________________ related
- at constant mass & volume
CONCEPT CHECK
Pressure decreases…
Temperature increases…
Volume increases…
Pressure decreases…
Temperature decreases…
Volume increases…
K. Combined Gas Law
SAMPLE PROBLEMS:
A gas occupies 473 cm3 at 36°C. Find its volume at 94°C.
Law:
Given:
Work:
3. A gas occupies 100. mL at 150. kPa. Find its volume at 200. kPa.
Law:
Given:
Work:
A gas occupies 7.84 cm3 at 71.8 kPa & 25°C. Find its volume at STP.
Law:
Given:
L. Avogadro’s Law
Work:
Equal Volumes of gases contain ________________________.
- At ___________________________
M. The Ideal Gas Law
R = Universal Gas Constant
R=0.0821 Latm/molK
R=8.315 LkPa/molK
n = number of moles
Ideal Gas Law Sample Problems
1. Calculate the pressure in atmospheres of 0.412 mol of He at 16°C & occupying 3.25L.
Given:
Work:
2. Find the volume of 85 g of O2 at 25°C and 104.5 kPa.
Given:
Work: