So HOW does matter change its state?
• Energy is what changes a phase of matter.
© 2013 S. Coates
What is energy?
Energy is
the ability
to do work
or cause
change.
Kinetic Energy
Kinetic Energy is the energy of
motion
Particles with
a lot of kinetic
energy
Particles with a lot of kinetic
energy move fast and far
apart (a gas)
Particles with little kinetic
energy move slow & close
together (a solid)
Particles with
little kinetic
energy
Temperature
Temperature is the
average kinetic energy
of the individual particles
in a substance
So… if it is hot, it has
more kinetic energy, if it
is cold, it has less kinetic
energy.
Changing states
Matter can
change from one
state to another
when thermal
energy is released
or absorbed.
This is called a
change of state.
Melting
The change from the solid
state to the liquid state is
melting.
The temperature at which a
substance changes from a
solid to a liquid is called the
melting point.
Melting is when matter
absorbs energy, and its
temperature rises.
Freezing
The change from the liquid state to
the solid state is called freezing.
The temperature at which a
substance changes from the liquid
state to the solid state is called the
freezing point.
Energy is released (decreases)
during freezing.
After all of the liquid has become a
solid, the temperature begins to
decrease again.
Vaporization
The change from a liquid
state to a gas state is known
as vaporization.
The temperature of the
substance does not change
during vaporization.
 However, the substance
absorbs thermal energy.
Vaporization
Two forms of vaporization exist.
Vaporization that takes place
below the surface of a liquid is
called boiling.
The temperature at which a liquid
boils is called the boiling point.
Vaporization that takes place at
the surface of a liquid is called
evaporation.
Evaporation
• Evaporation, which occurs at
temperatures below the boiling point,
explains how puddles dry up.
• It takes more than speed for water
molecules to escape the liquid state.
• During evaporation, these faster
molecules also must be near the surface,
heading in the right direction, and they
must avoid hitting other water molecules
as they leave.
Condensation
As a gas cools, its particles slow
down.
When particles move slowly
enough for their attractions to
bring them together, droplets of
liquid form.
This process, which is the
opposite of vaporization, is
called condensation.
The opposite of vaporization is condensation,
which occurs when a gas loses enough thermal
energy to become a liquid.
Where does the water on the outside of
the glass come from?
Sublimation
• Some substances can change
from the solid state to the gas state
without ever becoming a liquid.
During this process, known as
sublimation, the surface particles
of the solid absorbs enough
energy to become a gas.
Picture from
http://www.ehow.com/how_2098268_fogsmoke-dryice-halloween.html
Deposition
Deposition moving directly from a
gas to a solid state
The opposite of sublimation
State Change Pyramid
Absorbing
thermal energy
Gas
Releasing
thermal energy
Melting
Solid
Freezing
Liquid
Fill in the Blank
Phase change HW
1. liquid
Complete the Chart
2. solid
#
Change of State
3. freezes
1
Solid to Liquid
4. 0 C, 32 F
2
Liquid to Gas
6. water vapor
3
Gas to Liquid
7. evaporates
4
Liquid to Solid
8. dry ice
5
Solid to Gas
6
Gas to Solid
5. gas
9. liquid
10. 100 C, 212 F
Rise in Temp
Drop in Temp
Phases of Matter
•
ADDED
Is ENERGY being ADDED or TAKEN AWAY in this phase change:
The added energy has caused the
chocolate particles to speed up. Before
they were vibrating in place, now they are
moving fast enough to slip past one
another.
Solid
© 2013 S. Coates
Liquid
Phases of Matter
•
Is ENERGY being ADDED or TAKEN AWAY in this phase change:
ADDED
The added energy has caused the water
particles to speed up. Before they were
moving fast enough to slip past one
another, now they have enough energy to
break away from one another and expand.
Liquid
© 2013 S. Coates
Gas
Phases of Matter
•
Is ENERGY being ADDED or TAKEN AWAY in this phase change:
Taken Away
Taking away energy from a puddle slows
the water molecules down so that they no
longer slide past one another.
© 2013 S. Coates
Liquid
Solid
So What? How can I use this information?
Iceland sits on the
boundary of two platesthe North American Plate
and the Eurasian Plate.
Is it a divergent, convergent, or transform boundary?
What will we see happening at this type of boundary?
 The 1973 Heimaey eruption started on 23 January with the opening of a 1600 m long fissure on the east side of the
island, about 400 m east of the outskirts of the town. During the first hours lava issued from the entire fissure in 50-150 m
high glowing fountains. A day later the eruption continued from two craters, and on 6 February only one crater
remained, where activity continued until 26 June, when the eruption came to an end. By that time 417 houses had
been destroyed by lava and tephra and the remainder of the town was covered with millions of tons of tephra. The
total volume of the eruption products was 250 million cubic metres (230 million m3 as lava and 20 million m3 as
tephra). The chemical composition of the products is alkali basalt, murgearite to hawaiite.
 The 1973 eruption on the island of Heimaey is a classic example of the struggle between man and
volcanoes. With a heroic effort the people of Iceland saved the town of Vestmannaeyjar and the
country's most important fishing port.
 Except where noted, all photographs are by the late Svienn Eirikksen, fire marshal of the town of
Vestmannaeyjar. Photographs courtesy of the U.S. Geological Survey.
 The island of Heimaey with the growth of the island in 1973, the location of the
eruptive fissure, and the location of Eldfell, the 1973 cone. Modified from
Williams and Moore, 1983.
 Not only did the tremendous efforts save the port they actually improved it. The residents returned
to rebuild their town and even used the heat from the cooling lava to construct a district heating
system. This vertical aerial photograph of the island shows the improved harbor, Helgafell and
Eldfell cones, and the new land added to the island. Photograph by Iceland Geodetic Survey,
September, 8, 1973. From Williams and Moore, 1983.
http://www.youtube.com/watch?v=ghl33n26d44
The Cooling of Lava
State Change Pyramid
Absorbing
thermal energy
Gas
Releasing
thermal energy
Melting
Solid
Freezing
Liquid
Phase Change Lab
 1. Get goggles and bins from the back.
 2. Once your group is ready, ice and dry ice will be
placed in your petri dish.
 3. Make observations about the materials and
answer the questions on the back of your paper.
 4. Fill the beaker ½ way with water.
 5. Using your gloves, drop the dry ice into the
water.
 6. Observe the gas being produced- which way is
the gas flowing?
Conclusion Questions
1. & 2. What observations did you make about
dry ice and water?
3. How are the two substances similar?
4. How are they different?
5. What phase change did you observe for
each?
Dry Ice _________________
Frozen Water _______________
6. Why is it called “dry ice”?
7. What happens to the ice molecules
as they change to a liquid?
The water molecules (2 hydrogen and one oxygen) stay together
as a molecule, the elements do NOT separate from one another!
8. What happens to the dry ice
molecules as they change to a gas?
~Molecules spread apart and move
faster.
9. Are Ice and liquid water the same
thing? Explain
10. How could you change the liquid
water back to ice?
Metal Ring Demo- How will the molecules of the
metals change as they are heated?
Slime Time!
 Is slime a solid or a liquid?
 Background Information:
The three states of matter we are studying are ______. _______,
and ________
Molecules in the __________ stage move very little and have a
definite shape.
Molecules in the ____________ phase move around and slide
past each other and take the shape of their container
Molecules in the __________ phase are bouncing around freely
and do not have a constant volume or definite shape.