Kinetic Theory
Ch 16 Sect 1
Kinetic Theory

Explanation of how particles in matter
behave

There are 3 assumptions associated with
the kinetic theory
1.
2.
3.
All matter is composed of smaller particles
(atoms)
These particles are in constant random motion
These particles collide with each other and their
boundaries
Kinetic Theory and Energy
 The
movement of the particles
(atoms) with in an object depend on
energy
– Energy is measured as heat
– As energy increases (gets hotter)
particle motion increases
– As energy decreases (gets colder)
particle motion decreases
Measuring Particle Energy
There are 2 different measurements
used when measuring the energy within
an object

1.
Thermal energy-When using thermal energy
you measure the total amount of energy for
all of the particles in the object (substance)
– More thermal energy = More (faster) motion
– Less thermal energy = less (slower) motion
Measuring Particle Energy (cont)
2.
Average Kinetic Energy (AKE)-The average
kinetic energy shows the average energy for
all the particles in an object (substance)

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Most commonly know as the temperature of
an object (substance)
As temperature goes up the particles in the
object are moving faster
As temperature goes down the particles in the
object are moving slower
Finding Thermal energy and AKE
Balloon in Flask

The reason this experiment works is
because of the kinetic theory of the
particles in the flask
• As you heat up the flask the molecules begin
•
•
to move faster (causes them to escape)
You cap the flask with the balloon which traps
all of the particles (keeps other particles out)
Put in ice water and the energy decreases
which causes the molecules to move slowly
and come back together (sucks the balloon in)
States of Matter

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Matter-Anything that has mass
and occupies space
There are 3 common types of
matter on earth
• Solid, liquid, gas
4th type of matter is most common
and found in stars of our universe
• Plasma
Solid Matter
 In a solid the particles inside the object
are packed closer together


These particles have less energy then
liquid and gas states
Most solids have a specific geometric
arrangement for their particles
 Ex-Picture
of water on pg 489 of your text
book

Solids have a fixed shape and volume
Liquid Matter


As temperature increases the particles start
moving faster
Eventually they gain enough KE to
temporarily move past their boundaries
– Slide past each other
– More energy then solids but less then gases


Liquid has a fixed volume but not a fixed
shape
Solids melt to a liquid at heat of fusion
Gas Matter

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Gases have enough kinetic energy to
overcome all the attractions between
the particles
Gases have more energy then liquids
and solids
Gases do not have fixed volume or
shape
Liquids turn to gases when they hit the
heat of vaporization
Heating Curve (S to L to G)
1. As you start to heat up a solid the
temperature begins to rise
2. The temperature will rise till it
reaches the heat of fusion
– At this point all energy goes into
breaking away from chemical bonds
Heating Curve (S to L to G)
3. Once substance becomes a liquid
the temperature begins rising again
4. Temperature continues to rise until
it reaches the heat of vaporization
–
Once again energy goes into particles
breaking its chemical bonds
Gas to Liquid
•
There are two different ways a gas can go to a
liquid
1. Evaporation-One molecule overcomes the
attractive forces at a time.
–
Evaporation is slow enough that you cant see it happen
2. Boiling-Lots of molecules overcome the attractive
forces at a time
– Happens with high heat or low pressure
Pressure and States of matter
► Pressure
is the other variable that can affect
states of matter
 High pressure causes the molecules to stick to
be pressed together
►Can cause a gas to
 Example = Dry ice
go to a liquid or a liquid to a solid
 Low pressure allows the molecules to spread
out
►Can cause a solid to go to
 Example boiling cold water
a liquid or a liquid to a gas
Thermal Expansion
 Expansion of materials do to rising
temperatures
 Higher temperature = increase in size of
object
 Particles move faster/increase distance between
 Lower temperature = decrease in size of
object
 Particles move slower/decrease distance between
Diffusion

Movement of molecules from a high
concentration to a low concentration

Happens because of the law of entropy


Law of entropy states that everything will go
from a state of order to a state of disorder
unless energy is added to keep it organized
Will particles diffuse quicker in hot water or
cold water?
Making Ice Cream

To make ice cream we take a liquid (milk) and
other ingredients (for flavor) mix them
together and then take away thermal energy

Taking away the thermal energy causes the
molecules to slow down, which in turn causes the
state of matter to change from a liquid to a solid
Materials Needed for making Ice Cream
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1 gallon ziploc bag
1 quart ziplock bag
6 cups of ice
1/3rd cup of salt
1 cup of whole milk
1 teaspoon of vanilla or strawberry extract
2 table spoons of sugar
Procedure
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Pour milk, extract, and sugar into a small
bag (get any extra air out and seal it)
Place small bag in large bag and cover
with ice and salt (seal bag)
Shake bag until liquid solidifies

Usually 8-12 minutes
Ice Cream Lab

Which type of milk allows ice cream to
freeze faster?

Non-Fat or 2% fat