The document discusses the relationships between pressure, temperature, and volume in gases. It explains that gas pressure increases with temperature because the faster moving gas molecules collide with the container walls more frequently and forcefully. It also explains that gas volume increases with temperature as the molecules move further apart while maintaining a constant pressure through less frequent but more forceful collisions. Finally, it notes that gas pressure increases with decreasing volume, as molecules collide with the walls more often in a smaller space.

1. Motion of Molecules and Pressure
• Moving gas molecules collide with the inner
walls of the container and exert a force on it
• The force exerted per unit area is thus
called gas pressure.
PRESSURE IN GASES

2. Pressure−Temperature
Relationship of a Gas
• 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.
P Tµ

3. Volume−Temperature
Relationship of a Gas
• When the air is heated, the increased
temperature causes the air molecules to
move at higher speeds
• The air molecules will then bombard the
walls of their container more forcefully and
more frequently; gas pressure increases
• The air expands and the air molecules
move further apart causing the air
molecules to occupy a larger volume.
• They collide with the walls less frequently,
but more forcefully and maintaining
constant pressure V Tµ

4. More frequent collisions,
but each collision is less
forceful.
Less frequent collisions,
but each collision is
more forceful.
Same pressure
(atmospheric pressure)
Volume−Temperature
Relationship of a Gas

5. Pressure−Volume
Relationship of a Gas
• When the volume of the gas is decreased, the number
of air molecules per unit volume increases.
• The air molecules will therefore bombard the walls of
the container more frequently.
• This causes an increase in the force exerted on the
walls of the container, and hence an increase in the
gas pressure.
P V
1
µ