Kinetic Model of Matter Main Version

1. Kinetic Model of Matter
9.1 The States of Matter
9.2 The Kinetic Model of Matter
9.3 Pressure in Gases

2. Learning Objectives
• Distinguish between solids, liquids and gases
in terms of their physical properties.

3. States of Matter
• What can you recall from your prior knowledge?
• What is matter?
• What are the different states of matter?
• What are some properties of each state of matter?

4. States of Matter
State of Matter Properties
Solids •Fixed shape and volume
• Hard rigid
• High density
• Incompressible
Liquids •Fixed volume but no fixed shape
• High density
• Incompressible
Gases •No fixed shape and volume
• Low density
• Compressible

5. The Kinetic Model of Matter
Learning Objectives
• Describe the molecular structure of solids,
liquids and gases
• Infer from Brownian motion experiment the
evidence for the movement of molecules
• Describe the relationship between the
motion of molecules and temperature

6. States of Matter at a Molecular Level
• Using an applet, the three various states will
be looked at a microscopic level
• Keep these questions in your mind as we
explore the applet
1) How are the particles arranged?
2) How do the particles move?

7. States of Matter at a Molecular Level
Solid State Liquid State Gaseous State
 Particles are closely
packed together which
explains their high
densities
 Particles are held in
place by strong attractive
forces and vibrate about
their fixed positions which
gives them their fixed
shape and volume
 Particles are arranged
randomly and are slightly
further apart as compared
to the solid state, retaining
relatively high densities
 Particles have strong
attractive forces but are
not held in fixed positions,
allowing them to move
freely within the liquid,
resulting in a fixed volume
but no fixed shape.
 Particles are arranged
randomly and are very far
apart resulting in low
densities
 Weak attractive forces
between particles allows
them to move about
freely. Thus, they have no
fixed shape or volume.

8. Brownian Motion
• It is a random motion of particles
suspended in fluids caused by the random
movement and bombarding of the
suspended particles by the fluid particles

9. Brownian Motion
• Observe the video and describe Brownian
motion
• How does temperature affect Brownian
Motion?

10. Brownian Motion
• Let’s imagine dust particles that are
suspended in our atmosphere
• During a hot day, as the temperatures rise,
what would happen to the air molecules?
• What would be the resultant effect on the
dust particles that are suspended in the air?

11. Brownian Motion
• Temperature of air increases
• Average kinetic energy of air molecules
increases.
• Number of bombardments of air molecules
on smoke particles increases.
• Dust particles move faster and change
direction more frequently.

12. Pressure in Gases
Learning Objectives
• Explain the pressure of a gas in terms of the
motion of its molecules
• Recall and explain the relationships between
pressure, volume and temperature using the
kinetic model

13. Pressure in Gases
• What is Pressure?
• How do gases cause pressure?
Moving gas molecules collide with the inner wall of
the container and exert a force on it. The force
exerted per unit area is thus called gas pressure.

14. Gay-Lussac's Law
• At a higher temperature, the air molecules have greater speeds
(greater average kinetic energy).
• The air molecules will then bombard the walls of their container more
forcefully and more frequently.
• This causes an increase in gas pressure inside the container.
Consider a container filled with air. What
would happen if we increased the
temperature of the gas (i.e. the air) in the
container?

15. Gay-Lussac's Law
This law relates temperature and pressure
together.
The pressure, p, of a fixed mass of gas is
directly proportional to its temperature,
T, at constant volume.
P Tµ
when mass
and volume
are constant

16. Gay-Lussac's Law
P is the pressure of the gas
T is the temperature of the gas
(measured in Kelvin).
k is a constant

17. Charles’ Law

18. Charles’ Law
This law relates volume and temperature
together.
The volume,V, of a fixed mass of gas is
directly proportional to its temperature,
T, at constant pressure.
V Tµ
when mass
and pressure
are constant

19. Charles’ Law
; V/T = K (Constant) ; V1/T1 = V2/T2V Tµ
V is the volume of the gas
T is the temperature of the gas (measured
in Kelvin).
k is a constant

20. Boyle’s Law

21. Pressure - Volume Relationship
The pressure p of a fixed mass of gas is
inversely proportional to its volume V at
constant temperature.
when mass and
temperature are
constant
P V
1
µ

22. Boyle’s Law
;PV=Constant(K) ; P1V1 = P2V2P V
1
µ
P is the pressure of the gas
V is the volume of the gas
k is a constant

23. Combined Gas Law