Transcript Physical Characteristics of Gases

Physical
Characteristics of
Gases
The Kinetic
Molecular Theory of
Matter
Objectives
• List the physical properties of gases
• Use the KMT to explain the physical
properties of gases.
Kinetic Molecular Theory of Gases
• KMT- The particles of matter are in constant
motion.
Ideal Gas – a gas that behaves according to the
kinetic molecular theory.
Kinetic Molecular Theory of Gases
1. Gases are made up of
tiny particles.
- Usually atoms or
molecules
Kinetic Molecular Theory of Gases
2. The particles of a gas are
far apart from each other.
•
The volume of gas
particles is insignificant
relative to the space
between the particles
Kinetic Molecular Theory of Gases
3. The particles of a gas
are in constant motion
and collide with each
other and the walls of
their container.
• The collisions are
elastic; no K.E. is lost.
• Collisions exert a force
-pressure
• Specian's Phun
machines: Ideal gas –
YouTube
Kinetic Molecular Theory of Gases
4. The particles of a gas do not exert any force on each
other.
Kinetic Molecular Theory of Gases
5. Temperature is a
measure of the average
kinetic energy of the
particles of a gas.
1
K .E.  mV 2
2
Kinetic Energy in a Gas YouTube
Properties of Gases
Expansion of gases
• No definite shape or
volume
• Expand to fill their
container
Properties of Gases
Fluidity of Gases
• Gases have the ability to
flow.
Properties of Gases
Low Density
1 mole of H2O @ 20oC: 18 mL
1 mole of H2O @ 120oC and
1 atm: 22.4 L
Properties of Gases
Compressibility
• Gases can be easily
compressed
Properties of Gases
Diffusion and Effusion
Diffusion –mixing of
particles due to random
motion of particles
Effusion – process in
which gases past
through a tiny opening
Deviations from Ideal Gas Behavior
At low temperatures and
high pressures, gases
do not follow ideal gas
behavior.
1. The volume of the
particles is significant.
2. Intermolecular forces
become important.
Real gas – one that does
not behave according to
the KMT