Download Kinetic molecular theory and Gas Laws

Kinetic
Molecular
Theory &
Gas Laws
It’s all about the particles
•The molecules are in
constant motion. This
motion is different for
the 3 states of matter.
Solid - Molecules are held
close to each other by
their attractions of
charge. They will bend
and/or vibrate, but will
stay in close proximity.
•
Liquid - Molecules will
flow or glide over one another,
but stay toward the bottom of the
container. Motion is a bit more
random than that of a solid.
•
•
Gas - Molecules are in continual
straightline motion. The kinetic
energy of the molecule exceeds
the attractive force between
them. They are far apart and
move freely of each other.
When the molecules collide with
each other, or with the walls of a
container, there is no loss of
energy.
Pressure
• The pressure of a gas is caused
by collisions of the molecules
with the walls of the container.
Pressure (continued)
• The magnitude of the pressure is
related to how hard and how
often the molecules strike the
wall
Pressure (continued)
• The "hardness" of the impact of
the molecules with the wall will
be related to the velocity of the
molecules times the mass of the
molecules
Pressure
Absolute Temperature
• The absolute temperature (kelvin)
is a measure of the average kinetic
energy of its molecules
• If two different gases are at the
same temperature, their molecules
have the same average kinetic
energy
• If the temperature of a gas is
doubled, the average kinetic energy
of its molecules is doubled
Average Kinetic Energy
What is…..
•The effect of a volume
increase at a constant
temperature ?
Answer:
• Constant temperature means that
the average kinetic energy of the
gas molecules remains constant
• This means that the speed of the
molecules remains unchanged
• If the speed remains unchanged,
but the volume increases, this
means that there will be fewer
collisions with the container walls
over a given time.
What is…
•The effect of a
temperature
increase at
constant volume?
Answer:
• An increase in temperature means an
increase in the average kinetic energy of
the gas molecules.
• There will be more collisions per unit
time, furthermore, the momentum
(strength) of each collision increases
(molecules strike the wall harder)
• Therefore, there will be an increase
in pressure