# ppt

```Phases of Matter
Professor Lynn Cominsky
Joanne del Corral
Al Janulaw
Michelle Curtis
NBSP Physical Science
July 2, 2003
Standard Connections
Students know water can be a liquid or a
solid…(K)
 Students know solids, liquids and gases
have different properties (1)
 Students know matter has three forms:
solid, liquid and gas (3)

What are the phases of matter?
 What is the difference between solids,
liquids and gases?
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First Activity: What’s the Matter?
Write Yes or No in each box
Property
Solid
Liquid
Assumes the
shape of its
container
Can be formed into
a sphere
Crumbles
Flows
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What’s the Matter? Activity
Cornstarch (1/4 cup)
 Water (1/8 cup)
 Craft stick
 Measuring cup
 Ziplocs
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Mix ingredients together in the ziploc bag
using the stick.Stir quickly until the
material is smooth.
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Questions for What’s the Matter?:
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Does the material look like a solid or liquid ?
Why?
Poke your finger into the material. Does it
behave like a solid or liquid? Why?
Take a spoonful of the material in your hand
and roll it into a ball. How did it behave?
Now place the ball on the desk. How did it
behave?
Pick it up again and hold it for a few minutes.
Do you observe any changes that
demonstrate the presence of a gas?
Is this material a solid, liquid or gas?
Prof. Lynn Cominsky
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This material is often called “oobleck”
 A good children’s book that goes along
with this is Bartholomew and the
Oobleck by Dr. Seuss
 Oobleck is a type of
material known as a
Colloidal Suspension
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Key Concepts
Solids have a fixed shape and volume
 Liquids have a fixed volume but no
fixed shape.
 Gases have neither a fixed volume or
shape.
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Thinking deeper
In all 3 of these phases, the matter is in
the form of atoms or molecules.
 In solids, they are closely packed and
at relatively fixed positions.
 In liquids, they are closely packed, but
not in fixed positions.
 In gases, they are widely spaced and
not in fixed positions.
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Standard Connections
Students know the states of matter
(solid, liquid, gas) depend on molecular
motion (8)
 Students know that in solids the atoms
are closely locked in position and can
only vibrate; in liquids, the atoms and
molecules are more loosely connected
and can collide with and move past one
another; and in gases, the atoms and
molecules are free to move
independently, colliding frequently (8)
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Thinking Deeper: Particle Motion
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How do we know how much the atoms or
molecules move?
In solids, the vibration of the particles in the
lattice can be measured by sending in beams
of light of specific energies
In liquids,the movement of the particles is
responsible for its ability to flow and to
dissolve other substances
In gases, the motion of the particles and their
collisions with the walls of the container
creates gas pressure
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Thinking deeper: Phases of Matter
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Are there really 3 phases of matter?
If so, then what phase is the matter in
the Sun? How about the stuff inside
fluorescent light bulbs? Or fire?
Most everything in the Universe that is
luminous is plasma -a fourth phase of
matter, in which the atoms are ionized,
or disassociated. Plasma is a common
subject in physics, but is not studied in
chemistry (or in the standards.)
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Vocabulary
Solid – phase of matter that has fixed
volume and shape
 Liquid – phase of matter with fixed
volume but no fixed shape
 Gas – phase of matter with neither fixed
volume nor shape
 Note that all of these words have
different meanings in colloquial English
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ELD Activities: Academic Language
What are other meanings for the word
solid?
 Note that “gas” is often used as slang for
gasoline, which is a liquid, and has
nothing to do with the usage of the word
in this case.
 Why are some types of financial
accounts referred to as liquid?
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ELD Activities: Visual Imagery
Fill in the table below with common
items.
 Indicate whether the item is in the form
of solid, liquid or gas.
 Draw a picture of each item.
 Examples could include: water, ice,
steam. Others?
 Item
Phase
Drawing
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Publisher’s Materials
Take some time to look through the
state-adopted texts to find activities
relating to measuring and observing
objects
 Examples: HC Grade 2, p. C20
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Break: Something to think about
We are familiar with the effects that an
increase in temperature has on melting
solid ice to form liquid water, or heating
water to create water vapor (steam)
 Are there other ways to change
phases? For example, can you melt ice
without changing the temperature?
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Standard Connections
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Students know water can be a liquid or a solid
and can be made to change back and forth from
one form to the other (K)
Students know the properties of substances can
change when they are .. cooled or heated (1)
Students know evaporation and melting are
changes that occur when objects are heated (3)
How do we define temperature?
What are phase changes?
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Second activity – Defining temperature
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A thermometer consists of a
chamber or bulb of liquid with a
long narrow tube attached.
When the liquid inside becomes
hotter, it expands and moves up
the tube. When it cools, it
contracts and moves back
down. The level of the liquid can
therefore be used as a measure
of the temperature of an object.
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Galileo’s
thermoscope
c. 1597
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Second activity – Defining temperature
Given: beaker of water,
thermometer, hot plate
 Heat a beaker of water with
a thermometer in it.
 Record the temperature
every 30 seconds, until it
has been boiling at least 3
minutes.
 Graph the temperature vs.
time from your data.
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Questions for the Temperature activity
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Where on your graph does the water start to
boil?
Does the temperature of the water change in
the same way before it has begun to boil and
after?
Explain how you can tell from your graph.
How do we calibrate a thermometer?
Write an operational definition for
temperature.
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Key concepts
On the Celsius scale, the boiling point of
water is defined as 100o C, while the
freezing point is defined as 0o C.
 You can use these two fixed points to
define a temperature scale, and to
calibrate a thermometer.
 Water changes phase from liquid to gas
form when it boils.
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Thinking Deeper - Phase Changes
There is a complicated relationship
between temperature and pressure that
describes the phases of matter for a
substance.
 This relationship is summarized in a
phase diagram.
 For example, the boiling point of water
is 100o C at one atmosphere pressure,
but increases as the pressure
increases.
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Thinking Deeper – Phase Changes
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Thinking Deeper - Phase Changes
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Key Concepts: Phase Changes
Boiling can occur at much lower
temperatures than 100o C – if the
pressure is also much lower than 1 atm.
 Boiling therefore does not necessarily
mean hot – instead, it refers to the
process of changing liquid to gas
 Along the boiling point line, water vapor
and liquid water can both exist
 Heat is needed in order for the phase to
change from liquid to gas
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Key Concepts: Phase Changes
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The heat required to boil (1 g of) water
(without changing its temperature) is called its
heat of vaporization
Along the melting point line, ice and liquid
water can both exist
Heat is required in order to melt ice to liquid
water
The heat required to melt (1 g of) water
(without changing its temperature) is called its
latent heat of fusion
At the triple point, all 3 phases of water can
coexist
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Lunch puzzler
 Consider a figure skater.
 How does the phase
to understand what
happens when the skater
presses her blades on the
ice?
 In other words, how does
ice skating work?
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Standard Connections
Students know metals have properties in
common, such as high…thermal
conductivity (5)
 Students know heat flows in solids by
conduction (6)
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How can we measure thermal conductivity?
 What is the difference between
temperature and conductivity?
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Third activity: Thermal Conductivity
Given: blocks of plastic, wood and
aluminum that have been sitting out in
the classroom for a while
 Measure the temperature of each with a
thermometer. Do not hold them while
making the measurements – leave them
on the table
 Place the inside of your wrist against
each object. How do they feel?
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Third activity: Thermal Conductivity
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According to your operational definition, do
the two blocks have the same temperature?
Is it possible for two objects to feel different to
the touch and yet have the same
temperature?
Does the feeling of hotness or coldness give
a reliable indication of the temperature of an
object?
What is happening to make the objects feel
different?
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Fourth activity: Math connections
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It takes one calorie of heat to raise the
temperature of 1 g of water by 1o C. This is
known as the specific heat of water
The heat of vaporization (of 1 g) of water (at
100o C) is 540 calories. (This is how much it
energy it takes to turn 1 g of water into 1 g of
steam, without changing its temperature.)
Before and after vaporization, the water and
steam remain at 100o C.
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Fourth activity: Math connections
The heat of fusion (of 1 g) of water (at 0o
C) is 80 calories. (This is how much it
energy it takes to melt 1 g of ice into 1 g
of water, without changing temperature.)
Before and after melting, the water and
ice remain at 0o C.
 How much heat does it take to melt 10 g
of ice, heat the resulting water up to 100o
C, and then boil the water until 1 g has
turned into steam?
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Fourth activity: Math connections
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Standard Connections
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Students know water left in an open container
evaporates, but water in a closed container
does not (K)
Students know evaporation and melting are
changes that occur when objects are heated (3)
Students know physical processes include
freezing and boiling in which a material changes
form with no chemical reaction (8)
What is happening when water evaporates?
What is the difference between evaporation and
boiling?
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Key concepts: Evaporation
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Evaporation occurs when some of the
molecules at the surface of the liquid have
enough energy to escape as gas
In a closed container, these molecules stay
trapped as vapor
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Key concepts: Evaporation
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One way to estimate how much energy is
required to vaporize water at (for example)
20oC room temperature is
– Vaporize 1 g of water at 100oC = 540 cal
– Cool 1 g of steam from 100oC to 20oC = 40 cal (as
you get 0.5 cal when you cool 1 g of steam by 1
degree.)
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So the total heat needed to evaporate 1 g of
water at 20oC is about 580 cal. In other
words, 580 cal is removed from the mass of
liquid for every gram of water that
evaporates. This is why evaporation is a
cooling process.
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Key concepts: Evaporation vs. Boiling
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Since the vapor particles are a gas, they can
exert pressure on the liquid or on the walls
and top of the container. This pressure is
called the vapor pressure.
When a liquid boils, the vapor pressure is so
large that bubbles form throughout the liquid,
and carry the gas particles to the surface,
where they boil off.
During evaporation, the vapor pressure is
less than the air pressure, so no bubbles are
formed. Vapor particles only leave from the
surface.
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Key concepts: Evaporation vs. Boiling
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Standard Connections
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Students know heat flows… in fluids by
conduction and convection (6)
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Consider a pot water on an electric hot plate,
which has been boiling steadily for some time
Describe all of the heat transfers taking place
at the interfaces between the different
elements: air, water, pot, hot plate
What type of heat transfer is taking place at
each interface?
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Thinking Deeper: Heating and Cooling
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It is possible to keep foods quite cold
without a refrigerator by wrapping them in a
towel soaked in cold water. Why does this
procedure work?
In many places, it takes
weeks or months for snow
that accumulated during the
winter to melt. Why doesn’t
all of the snow melt as soon
as the temperature climbs
above 0oC?
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Thinking Deeper: Evaporation &amp; Melting
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Students know evaporation and melting are
changes that occur when objects are heated (3)
Is this third grade standard strictly true?
It requires energy to melt an object (heat of
fusion) BUT…
Evaporation can occur without heating an
object. In fact, it cools an object as it removes
the heat of vaporization.
Heating enhances the rate of evaporation, but it
is not necessary.
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Thinking Deeper: calories and Calories
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We have defined a unit of heat (energy)
known as a calorie. For example, it takes 1
calorie to heat 1 g of water by 1 degree C.
The calories that are used in discussing the
energy content of food are usually written as
Calories (capital C). These Calories are equal
to1000 times the heat calorie (lower case c),
so they are also called kilocalories (kcal).
How much would a 200 Cal candy bar cause
a 50 kg person’s temperature to rise (if they
could not cool off)? Assume the person is
made entirely of water.
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Vocabulary
Boiling – process where heat is added to
turn a liquid into a gas
 Freezing – process where heat is
removed to turn a liquid into a solid
 Melting – process where heat is added
to turn a solid into a liquid
 Condensation – process where heat is
removed to turn a gas into a liquid
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Vocabulary
Evaporation – surface process where
a liquid turns into a gas, removing heat
from the liquid
 Conduction – direct transfer of heat
from one object to another
 Convection – transfer of heat by the
formation of gas bubbles within a liquid
that is unevenly heated
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Why do we say someone that is very angry
Why do we say someone who is motionless
is frozen in place?
Think of other common uses of the
vocabulary words that describe human
behavior, rather than physical phenomena
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ELD Activities: Analogies and Student
Involvement
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Ask the students to record their Caloric intake
for a day and make a list of what they did
during that day (school work, activities,
sports, etc.)
With the help of a reference book (Health
book for example), have them compare their
food calorie (C) intake, converted into energy
(c), with how much energy they needed to do
all the activities they were involved in during
that day.
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Publisher’s Materials
Take some time to look through the
state-adopted texts to find activities
relating to phase changes that could be
used in your classroom.
 Examples: HC p. C12
 HC gr. 2 C27
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Break: Vaporization Challenge
Which will burn more? A gram of boiling
water at 100o C that hits your skin (at a
temperature of around 40o C) or a gram
of steam at 100o C?
 Why?
 Explain your reasoning.
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Equipment for Fifth Activity: Dry Ice
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Dry Ice
2 Tweezers,
2 Medicine Droppers
2 Balloons
4-5 Clear Plastic Cups
Hot and Cold Water
2 Pennies
1 Ziploc Bag
2-3 Plastic Spoons
Newspaper to cover work area
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Dry Ice Activity Investigations:
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Put a tiny piece of dry ice in water (cold then
hot). What happens? Try poking it with a
pencil or tweezers.
Put drops of cool water on a piece of dry ice.
Note what happens
Press something metal against the dry ice.
What do you hear?
Put the dry ice in a graduated cylinder, seal it
with a balloon.
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Questions about the Dry Ice Activity
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Where do you think the gas is coming from
that filled the balloon?
How could so much gas/air come from a tiny
piece of ice?
Since the cylinder is sealed, and more “stuff”
can’t get in, why are the contents taking up
more space and filling the balloon?
Why do you think the water rolls off the dry
ice?
Why do tiny floating pieces of dry ice move
away from one another?
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Further Investigations with Dry Ice
What will happen to the dry ice if you
place it in a soapy solution?
 Does it matter how much dry ice is
placed in the soap solution?
 Does it matter how much soap is used
in the solution?
 Does it matter what kind of container we
use?
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Further Questions for Dry Ice Activity
Does dry ice always
produce bubbles?
 What do you think is
making the bubbles?
 What is inside the bubbles
and where did it come
from?
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Key Concepts: Sublimation
Materials like CO2 have phase
diagrams that show a different
relationship between pressure and
temperature compared to water
 At atmospheric pressure, CO2 is a solid,
which changes directly into a gas
 This process is called sublimation
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Phase Diagram for CO2
liquid
solid
gas
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Compared to 1 atm and room
temperature, what type of conditions are
necessary for CO2 to appear in liquid
form?
 If the temperature is held constant, what
must happen in order for CO2 to boil ?
 What must happen in order for CO2 to
freeze?
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Standard Connections
Students know properties of solid, liquid
and gaseous substances, such as water
(H2O) .. and carbon dioxide (CO2). (5)
 What differences did you observe
between water and carbon dioxide at
room temperature?
 What phases will these substances be in
at a temperature of 100o C?
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Lesson Study Activities
Identify a key concept from today’s
lecture for further development
 Review the publisher’s materials about
this key concept
 Think about best way to present this key
concept in your classroom
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Resources
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Physics by Inquiry – L. McDermott and the
PEG at U Washington
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http://www.chem.uidaho.edu/~honors/phases.html
http://www.galaxy.net/~k12/matter/phases.shtml
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http://server.chem.ufl.edu/~itl/2045_s99/lectures/lec_f.html
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http://galileo.imss.firenze.it/museo/4/eiv07.html
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http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html#c3
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http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/vappre.html
http://purcell.phy.nau.edu/courses/02/spring/sci420/stuproj/webpages/sackey_si
o/water/water4.jpg
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GEMS DRY ICE Activities by J. Barber, LHS
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