Name_____________________________________________ # _____ Per. _____
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Chapter 12: The Kinetic-Molecular Theory
Section 12-1 reference p. 421-422
Kinetic-Molecular Theory

theory based on the idea that particles of matter are __________ __ _________
 helps explain the _________ and __________ of gases using a model called the
ideal gas
 kinetic energy-energy of _______
 temperature-measure of the _________ _________ _________ of the particles of a
sample of matter
Ideal Gas

an ideal gas is an ______________ gas that fits all 5 assumptions of the kineticmolecular theory
 the kinetic-molecular theory ________ __ ______________
Assumption #1: Gases consist of large numbers of tiny particles that are far apart for
their size.
 gas particles commonly occupy a space ________ greater than the volume
occupied by the same particles in a _________ or ________ state
 most of a gas’s volume is _______ _______
 because of all this empty space, gases are ________ _______________
Assumption #2: Collisions between gas particles and between particles and container
walls are elastic.
 elastic collisions result in ___ ____ _____ of kinetic energy
 kinetic energy is ______________ between 2 particles during collisions
 the _____ ________ ________ of the 2 particles remains the ______ as long as the
______________ remains ___________
Assumption #3: Gas particles are in continuous, rapid, random motion Therefore they
possess kinetic energy.
 as gas particles cool, they slow down, losing kinetic energy and allowing attractive
forces between the particles to condense the gas into a liquid state
 gas particles move in ____ _____________
 this kinetic energy overcomes any _______________ forces between the particles
 as gas particles _______, they _______ down, ___________ kinetic energy and
allowing forces between the particles to ____________ the gas into a liquid state
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Assumption #4:There are no forces of attraction or repulsion between gas particles.
 when gas particles collide, they don’t stick together but immediately _________
______
 lack of attraction means the particles ___ ____ ______ ___ on approach
 lack of repulsion means there is ___ ______ _____ away from each other
Assumption #5: The average kinetic energy of gas particles depends on the
temperature of the gas.
KE = ½ mv2
KE means _________ _______
m means ______
v means velocity (______)

an increase in ______________ increases the kinetic energy (_________
proportion)
 an increase in ______________ increases the average _______ of the gas particles
(________ proportion)
 all particles of the same gas have the same ______, so the KE of any particular
particle depends on its average speed (m is __________)
 if particles in a mixture of gases all have the same _______________, their
KE is the same (KE and temperature are constant)---so lighter gases must be
moving ________ than heavier ones ( m and v are inversely proportional)
 at the same _________________, lighter gases move _________.
Kinetic-Molecular Theory and the Nature of Gases

the kinetic-molecular theory only applies to ideal gases
 but ideal gases ___ ____ ___________ exist
 many gases behave like ideal gases if they are at low pressure and high
temperature
 the __________-____________ theory accounts for many of the properties gases
actually exhibit
Ideal Gas Conditions:

______ temperature
 _____ pressure
 particle size is _______ compared to space between particles
 ________________ between particles are _________________
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Nature of Gases
Expansion
 gases have no ___________ _______
 gases will expand to _____ the container
Fluidity
 gases are _________
 because no attractive forces exist between particles they _________ past each
other
Nature of Gases-Low Density
 gases are mostly _________ space
 the density of a gas is about __/________ of its density in a _______ or _______
state
Nature of Gases-Compressibility
 because a gas is mostly empty space it can be ______________________, crowding
the particles __________ _______________
 pressurized gas cylinders can contain up to _______x the particles
as in a similar sized, non-pressurized container
Nature of Gases-Diffusion
 gases will __________ out and ______ together without being stirred
 this ________________ mixing, caused by random motion is called diffusion
 the rate of diffusion depends on __________ things:
o the _________ of the particles
o the ______________ of the particles
o the _______________ forces _____________ the particles
Nature of Gases-Effusion
 the movement of gas particles through a tiny _____________is called effusion
 the effusion ______ of a gas is ___________ proportional to its ___________
 molecules of ____________ gases effuse __________ than heavier gases
 (remember the mass and velocity of gas particles at the same temperature are
inversely proportional) KE = ½ mv2
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Deviation from Ideal Behavior
 real gas-a gas that does not behave completely according to the 5 assumptions of
the kinetic-molecular theory
 at ______ pressures and ____ temperatures gas particles can _________ each
other and move closer together causing “deviant behavior”
Non-Ideal Conditions
 _____ pressure
 _____ temperature
 particle size _________________compared to space between particles
 interaction between particles is ___________________
Deviation from the Ideal (cont.)

because noble gases exert very __________ ___________________ for each other
they ___________ “ideally” over a large range of temperatures and pressures
 diatomic gases like N2 and H2 are ____ ___________ and ____________ more
“ideally” than polar
gases
 ________ gases have a greater degree of “deviation” due to the _______________
forces between the particles