Gases
Chapter 10/11
Modern Chemistry
Sections 10.1, 11.1-11.3
The Kinetic Molecular Theory of Matter
Gases and Pressure
The Gas Laws
Chapter 8 Section 1 Describing
1
Gas
and the Ideal Gas Law
ChemicalVolumes
Reactions p. 261-275
Section 10.1
The Kinetic
Molecular
Theory of
Matter
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
2
KMT Animation
Insert Holt Visualizing Matter Disc 2
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
3
Kinetic Molecular Theory of Gases
• Based on the idea that particles of matter are
always in motion.
• Explains the properties of gases, liquids and
solids in terms of energy of particles and the
forces that act between them.
• Provides a model of an ideal gas
• Ideal gas: A hypothetical gas that perfectly
fits all the assumptions of the kinetic
molecular theory.
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
4
KMT Animation
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
5
Kinetic Molecular Theory
1. Gases consist of large numbers of tiny
particles that are far apart in relation to their
size.
TINY PIECES – LARGE SPACES IN BETWEEN
2. Collisions between gas particles and
between particles and container walls are
elastic collisions
ELASTIC COLLISIONS - NO ENERGY LOSS
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
6
Kinetic Molecular Theory
3. Gas particles are in continuous, rapid
random motion. The particles have kinetic
energy.
PARTICLES ARE IN MOTION
4. There are no forces of attraction between
gas particles.
NO FORCES OF ATTRACTION
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
7
Gas Particle Motion
Gas particles gravel
in a straight-line
motion until they
collide with each
other or the walls of
their container.
p. 330
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
8
Kinetic Molecular Theory
5.The temperature of a gas depends on the
average kinetic energy of the particles.
AVERAGE KINETIC ENERGY…TEMP
K.E. =
1
2
m v2
m = mass v = velocity
All the particles in a sample of gas have the same
mass so K.E. depends only on velocity
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
9
Temperature and K.E.
Insert Holt Visualizing Matter Disc 2
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
10
What is your ideal?
The KMT
applies
only to
IDEAL
gases.
Gases
behave
ideally
most of
the time.
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
11
Ideal vs. Real Gases
•
•
•
Gases behave ideally at common
temperatures and pressures.
At high pressures and low temperatures
gases behave non-ideally.
Polar gases deviate from ideal behavior more
than nonpolar gases
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
12
Expansion
• Gases completely fill their container.
– Particles move rapidly in all directions. (3)
– There are no attractions between particles. (4)
Fluidity
• Gas particles glide past each other to flow.
– There are no attractions between particles. (4)
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
13
Low Density
• The density of a gas is 1/1000th of a liquid or
solid.
– Particles are far apart. (1)
Compressibility
• Molecules of a gas can be pushed together
and the volume decreased.
– Particles are far apart. (1)
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
14
Gas Properties Animaiton
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
15
Diffusion
• The spontaneous mixing of the particles of
two substances
– Particles move rapidly. (3)
– Particles are far apart. (4)
– caused by their random motion.
p. 331
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
16
Diffusion vs. Effution
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
17
Effusion
• A process by which gas particles pass
through a tiny opening.
• The rate of effusion is directly proportional to
the velocity of the particles…so…
low mass particles diffuse faster.
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
18
Particle Mass & Effusion
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
19
Ch 10 Sec 1 Homework
Page 332 # 1-7
Chapter 10 Section 1 Kinetic
Molecular Theory p. 329-332
20