Chapter 3 Physical and Chemical Changes

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Chapter 3 Physical and Chemical Changes

• Question? What keeps the oranges from freezing?

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Section 3 - 1 Phases of Matter

• I. Physical Properties
• A. Characteristics of a substance that can
  be
• observed without changing the
  identity of the
• substance
• 1. Phases
• a. Physical property of matter
• b. Solid - liquid - gas - plasma
• B. Solids
• 1. Definite shape and definite volume
• 2. Crystals
• a. Particles are arranged in a
  regular, repeating
• pattern

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Solid, Liquid, Gas
(a) Particles in solid (b) Particles in
liquid (c) Particles in gas
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• 3. Amorphous solid
• a. Slow-moving liquid
• b. Wax, glass, tar
• C. Liquids
• 1. No definite shape
• a. Takes the shape of the container
• 2. Definite volume
• a. Cannot be compressed
• 3. Viscosity
• a. Resistance of a liquid to flow
• b. Oil viscosity breakdown

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Solid, Liquid, Gas
(a) Particles in solid (b) Particles in
liquid (c) Particles in gas
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• D. Gas
• 1. No definite shape and no definite volume
• 2. Can be compressed Jaws scene
• 3. Particles can spread apart
• a. Odor traveling through the room
• 4. Particles can move closer together
• a. Bike/car tire
• 5. Particles constantly moving
• a. Moves in all 3 phases
• b. As a gas, 10 billion collisions/sec
• c. Collisions with walls causes pressure

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Solid, Liquid, Gas
(a) Particles in solid (b) Particles in
liquid (c) Particles in gas
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Gas, Liquid, and Solid
Gas
Liquid Solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 441
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• E. Boyles Law
• 1. The volume of a fixed amount of gas
  varies
• inversely with the pressure of the
  gas
• 2. Temperature must be constant
• 3. If the volume doubles then the pressure
  is
• cut in half
• 4. P1 V1 P2 V2
• 5. Video

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(No Transcript)
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Boyles Law
Timberlake, Chemistry 7th Edition, page 253
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Boyles Law Illustrated
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 404
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• F. Charles Law
• 1. The volume of a fixed amount of a gas
  varies
• directly with the temperature of the
  gas
• 2. Pressure must be constant
• 3. If the temperature of a gas increases
  then the
• volume of the gas increases
• 4. T1 V2 T2 V1
• 5. Video

Jacques Charles (1746 - 1823)
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Charless Law
Timberlake, Chemistry 7th Edition, page 259
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Worksheet 1

• P 1 V 1 P 2 V 2

V2
40 N/cm2

180 m3

47 N/cm2

___________________
___________________
47 N/cm2
47 N/cm2

V2
153.19
m3
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Worksheet 2

• T 1 V 2 T 2 V 1

37 0 K

V 2

30 0 K

85 cm3
___________________
___________________
37 0 K
37 0 K
V2

68.92
cm3
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Worksheet 3

• P 1 V 1 P 2 V 2

P2
97 m3
40 N/cm2

180 m3


___________________
___________________
97 m3
97 m3

P2
74.23
N/cm2
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Worksheet 4

• T 1 V 2 T 2 V 1

T2
45 0 K

107 cm3


85 cm3
___________________
___________________
85 cm3
85 cm3
56.65

T2
0K
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• G. Avogadros Law
• 1. Relates the number of particles to its
  volume
• 2. Equal volumes of gases at the same
• temperature and pressure contain
  equal
• number of particles
• 3. A mole is a counting unit for chemist
• 4. A mole equals 6.02 x 1023
• H. Plasma
• 1. Rare on earth
• 2. Most common in the universe
• a. Stars (sun)

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THE MOLE

• 1. Would a mole of rice grains fill up the room?
• One mole of rice grains would cover all of
  the land area of planet earth to a depth of 75
  meters.
• 2. One mole of rice grains is more grains than
  the number of grains of all grain grown since the
  beginning of time!
• 3. A mole of rice would occupy a cube about 120
  miles on each edge!

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• 4. Computers can count at the rate of about 80
  million counts per second. At this rate it would
  take a computer a quarter of a billion years to
  count 6.02 x 1023.
• 5. In order to put a mole of rain drops in a 30
  meter diameter tank (100 ft), the sides of the
  tank would have to be 280 times higher than the
  distance from the earth to the sun!
• 6. A mole of hockey pucks would be equal to the
  mass of the moon!
• 7. Assuming that each human being has 60 trillion
  (6 x 1010 cells) and the world population is 4
  billion (4 x 109), the total number of living
  human body cells on the earth at the present time
  is 2.4 x 1023, or less than half a mole.

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• 8. If one mole of pennies was divided up and
  given to every person on earth, each person would
  receive 1.5 x 1014 pennies.
• Personal spending at the rate of one million
  dollars per day would use up each persons wealth
  in just over four thousand years.
• Life would not be comfortable, though the
  surface of the planet would be buried in copper
  coins to a depth of about 420 meters!

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• 9. If you had a mole of pennies and you wanted to
  buy kite string, you would get your moneys
  worth, even if you had to pay a million dollars
  an inch for your string! Imagine you were to
  stretch this string around the earth one million
  times and to the moon and back twenty-five times.
  You would still have enough string left over to
  sell it back at a penny an inch (a decided loss).
• With the funds this would bring you, you
  could buy every single person in the U.S. a
  5000 automobile and provide them with enough
  gasoline to run it non-stop at 55 mph for a year.
  Even after this, you would still have enough
  money to give every person in the world 9,024!
• (The basis for calculations earths
  circumference 25000 miles distance to the moon
  240,000 miles cost of gasoline 1.20 /gallon
  U.S. population 220 million world population
  4,020 billion)

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Section 3-2 Phase Changes

• A. Energy
• 1. Determines the phase a substance is in
• 2. Gas - most energy
• 3. Solid - least amount of energy
• a. ice - water - steam
• b. steam burn is worse than hot water
• B. Physical Changes
• 1. Changes of phases are examples
• 2. Def - changes from one form to another,
• but remains the same substance
• 3. No new forms of different kinds of
  matter formed
• 4. No new chemical properties

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• C. Melting (melting blocks)
• 1. Change from a solid to a liquid
• 2. Absorbs heat energy
• 3. Melting point
• a. Temperature at which a solid
  changes to a liquid
• b. Property of matter
• - ice 0 C -salt 801 C
• D. Freezing
• 1. Change from a liquid to a solid
• 2. Freezing Point
• a. Temperature at which liquid
  changes to a solid
• b. Ethylene Glycol (antifreeze) -37
  C

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• E. Vaporization
• 1. Phase change from liquid to a gas
• 2. Evaporation
• a. Vaporization occurring at the
  surface of a liquid
• b. Cooling process gt sweat
• c. can take place at any temperature

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Evaporation
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Korey Stringer
1974 - 2001
Korey Stringer was a professional football player
for the Minnesota Vikings. He collapsed during
practice from excessive heat and died the
following day.
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• 3. Boiling
• a. occurs at definite temperature
• b. affected by air pressure
• - lower air pressure lower b.p.
• - high altitude cooking instructions

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Boiling
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Effect of Pressure on Boiling Point
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• F. Condensation
• 1. Phase change from gas to a liquid
• 2. Examples
• a. shower mirror c. cold drinks
• b. dew d. rain
• G. Sublimation
• 1. Phase change from solid to a gas
• 2. Completely skip the liquid phase
• 3. Examples
• a. snow - ice in a freezer
• b. dry ice
• c. moth balls

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Condensation
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Heating / Cooling Curve of Water
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 445
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Energy and Phase Change
Adding heat at a constant rate
T
Boiling
Melting
Time
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Liquids
The two key properties we need to describe
are EVAPORATION and its opposite CONDENSATION
add energy and break intermolecular bonds
EVAPORATION
CONDENSATION
release energy and form intermolecular bonds
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States of Matter
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Energy Changes Accompanying Phase Changes
Gas
Condensation
Vaporization
Sublimation
Deposition
Energy of system
Liquid
Melting
Freezing
Solid
Brown, LeMay, Bursten, Chemistry 2000, page 405
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Section 3-3 Chemical Properties and Changes

• A. Chemical properties
• 1. Describe how a substance changes into
  other
• new substances
• 2. Flammability
• 3. Supports burning
• 4. Reacts with acids/bases
• 5. Reaction with other elements

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• B. Chemical Change
• 1. Process by which substance changes
• 2. Examples
• a. Burning of wood
• b. Souring of milk
• c. Digestion of food
• d. Decaying of plants/animals
• e. Rusting of iron