Chapter 3
Solids, Liquids, Gases
Mrs. Yakulis
Section 1 States of Matter
• Solids, liquids and gases are in
different phases or states
• Physical form that a substance can
exist
• Depends on how fast particles of
matter are moving due to energy
and how much attractive force they
have
Atoms and molecules
•
•
Small particles that make up
matter
Always in motion
Solids
• Definite shape and volume
• Particles very close together
• Vibrate in place (slow movement)
Solids are formed from the
building up of repeating
patterns of atoms and
molecules (particles)
Solids can be:
Crystalline
Amorphous
Long chain Polymers
Amorphous
• Atoms have no particular order
• Ex: rubber, wax, plastic
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Crystalline
Repeating pattern of rows
Orderly 3-D arrangement
Iron, diamond, ice
Liquid
•
Definite volume, takes shape of container
• Is a fluid- substance that flows
•
Move fast enough to overcome attractive force
between particles
• Loosely connected and can slide past one another
•
Particles are close together, difficult to push closer
•
Used in hydraulics
Properties
• Surface tension
•
Force acting on particles at the surface
of the liquid that cause liquid to form
spherical drops
•
Viscosity
•
Liquids resistance to flow, more
viscous, harder to flow
•
All fluids have different viscosities
Gas
•
•
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No definite shape or volume
Takes the shape of the container
Particles move fast enough to
completely break away from each other
(less attractive force than liquids)
•
Empty space between particles- can be
compressed
• Particles are free to move independently
and freely
Plasma
• Most common state of matter in the
universe sun and other stars made of
plasma
•
No definite shape or volume
•
Particles break away from each other,
AND particles themselves break apart to
form ions (charged particles +,-)
•
Conduct electrical currents
• On Earth: fire, lightning, auroras natural
•
Artificial: fluorescent lights (electric
charge pass through gases)
• How can a cylinder of
helium gas fill 700 balloons?
The behavior of gases
• When working with gases, it is helpful to
know:
• 1) Volume- space the gas particles occupy
• 2)Temperature- measure of average
kinetic energy of particles
• 3) Pressure- force of gas outward push
divided by the area of the walls of the
container
Pressure
•
•
•
Amount of force in a given area
Pressure is exerted on the inside of
balloons, basketballs, and all
containers with gas inside
• Gases will move from an area of high
pressure to an area of low pressure
• Units of
Pressure=Pascals=force/area=N/m2
• Earth's atmosphere is a layer of gases
surrounding the planet Earth and retained
by the Earth's gravity. It contains roughly
78% nitrogen and 21% oxygen, trace
amounts of other gases, and water vapor.
This mixture of gases is commonly known
as air. The atmosphere protects life on
Earth by absorbing ultraviolet solar
radiation and reducing temperature
extremes between day and night.
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Since all gas molecules spread out
the same way, equal volumes of
gas under equal conditions of
temperature and pressure will
contain equal numbers of
molecules of gas. 22.4 L of any
gas at STP (1.00 atm and 273K)
will contain one mole
(6.02 X 1023) gas molecules.
• Since there is space between gas
• molecules, gases are affected by
• changes in pressure.
• Why does an air bubble expand to twice
the size when traveling from beneath the
ocean to the surface?
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•
http://www.eoascientific.com/campus/ocean/multimedia/sea_pressure/view_interactive
http://my.hrw.com/sh/hpc/0030358337/student/ch03/sec01/qc08/hpc03_01_q08fs.htm
Boyle’s Law
• A fixed amount of gas at a constant
temperature will increase in volume as the
pressure decreases and vice versa
• Increase V, Decrease P
http://www.upscale.utoronto.ca/IYearLab/Intros/BoylesLaw/BoylesLaw.html
Charles’s Law
•
A fixed amount of gas a constant
pressure will increase in volume if the
temperature increases
•
(Increase of temperature causes
particles to speed up, colliding with the
sides of
the container more often with
a greater force, pushing it outward)
• Increase T, Increase V
Before refrigeration
After refrigeration
Section 2 changes of state
• Change from a solid to liquid to gas or
change from a gas to liquid to solid
• Is a “change of state” or “phase change”
• Conversion of substance from one
physical form to another
• Physical change
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•
Identity of substance does not change (no new substance
•
made)
Ex: Water- steam (water vapor, gas), liquid water, ice
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Earth's water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the
continuous movement of water on, above, and below the surface of the Earth. Since the water cycle is truly a
"cycle," there is no beginning or end. Water can change states among liquid, vapor, and ice at various places in
the water cycle, with these processes happening in the blink of an eye and over millions of years.
Although the balance of water on Earth remains fairly constant over time, individual water molecules can come
and go in a hurry. The water in the apple you ate yesterday may have fallen as rain half-way around the world last
year or could have been used 100 million years ago by Mama Dinosaur to give her baby a bath.
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Energy of substance changes (motion
of particles)
•
More energy, particles move faster
•
Gas has more energy than liquid, which
has more energy than solid
Heat is the energy that
transfers (in phase changes)
• Causes temperature to change or
• Can lead to a change of state
•
Temperature is measure of speed of
particles or energy of substance
Melting
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•
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Change of state from solid to liquid
Ex: Ice to liquid water
Melting point: temperature at which
substance changes from solid to
liquid
•
Different for different substances
Heat is absorbed, Is endothermic
(endo= into) (therm=heat)
•
Heat energy causes the particles to increase motion until enough
energy to overcome attractive force of particles
Freezing
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Change of state from liquid to solid
Temperature at which substance
freezes is the freezing point
Heat energy is removed is
– exothermic (exo=out of)
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Enough heat is removed to cause particles to slow down and pulled
into more orderly arrangement
• Freezing and melting point is the same
for substances!
• 0 degrees C for fresh water
Vaporization
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•
Change of state from liquid to a gas
Is endothermic
Boiling:
• Vaporization occurs throughout the
liquid
• Occurs at boiling point
• Different substances have different
boiling points
•
Fresh water boils at 100 C at sea level
(atmospheric pressure is 101,000 Pa
Pascal SI unit for pressure)
•
1N/m2 = 1Pa
• Atmospheric pressure increases at lower elevation (more
air), less at high elevation
• Water boils at less than 100 degrees at high elevation
• Less air pressure, easier for particles to escape into air
Evaporation
• Vaporization occurs at surface of a
liquid
• Occurs below boiling point
•
When a person perspires, the sweat evaporates
• Why is sweating considered a cooling
process?
Condensation
• Change of state from a gas to a liquid
• Same as boiling point
• Is exothermic, energy released
•
Particles clump together when attractive force overcomes their
motion
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http://my.hrw.com/sh/hpc/0030358337/student/ch03/sec02/qc09/hpc03_02_q09fs.htm
Sublimation
• Change of state from a solid directly to
a gas
• Endothermic
Deposition, also known as desublimation,
in which gas transforms into solid. The
reverse of deposition is sublimation.
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One example of deposition is the process by which, in sub-freezing air, water vapor
changes directly to ice without first becoming a liquid. This is how snow forms in
clouds, as well as frost on the ground.
When a substance gains or
loses heat energy either
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temperature changes or
state changes
• While a substance changes state, the
temperature does not change until the
phase change is complete
• What temperature is fresh water after it
has been boiling for 10 minutes?
• The heat transfer during a phase change
is used to break or make the attractive
forces between particles, it does not
change the kinetic energy of the particles
or change the temperature during a phase
change