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SOLIDS, LIQUIDS,

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CHAPTER 2 SOLIDS, LIQUIDS, & GASES I. States of Matter - A. Solids - have definite volume & definite shape In a solid, the molecules are tightly bound together ... – PowerPoint PPT presentation

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Title: SOLIDS, LIQUIDS,


1
CHAPTER 2
  • SOLIDS, LIQUIDS, GASES

2
I. States of Matter -
matter can exist in the universe in 4 states or
phases - solid, liquid, gas, plasma
  • A. Solids - have definite volume definite
    shape

3
1. Particles in a solid - are packed
tightly together - stay in fixed
positions - shape - are hard to separate
4
  • In a solid, the molecules are tightly bound
    together -
  • which holds a shape.
  • They vibrate in place

(Molecular Motion)
5
2. Types of Solids
  • a. Crystalline solids - particles form regular
    repeating patterns

Iron pyrite
6
- ex.s sugar, salt, sand, snow
  • Melting point - the distinct temp. at which a
    crystalline solid melts.

The crystal structure of snow
7
The molecular structure of salt a
microphotograph of salt crystals.
8
b. Amorphous Solids
  • Particles are not arranged in regular patterns.
  • Do not have distinct melting point temperatures
    (just get softer softer)
  • behave like slow moving, super-cooled liquids

9
- Can lose their shape under certain
conditions Ex.s - plastics, rubber, glass, wax,
tar
10
Wax - an amorphous solid
11
B. Liquids
(Molecular Motion)
  • No definite shape but a definite volume - takes
    on the shape of its container.
  • Particles not held as closely together - free to
    move - flow.

12
- 100 mL of water 100 mL in any shaped
container. (Definite volume)
13
  • Liquids do not easily compress or expand.
  • Viscosity - (a property of liquids) is the
    resistance of a liquid to flow
  • - honey has a high viscosity compared to water

14
Is lava liquid? Is it viscous?
15
C. Gases
  • Have no definite shape or volume - volume can
    change.
  • Will fill any available space - a small amount of
    gas can fill a large volume.
  • Will expand without limit.

16
-Gases can be compressed. A larger amount
forced into a smaller space. (A change of
volume)
17
The tanks worn by this diver contain several
hours of air. How does this work?
18
(Molecular Motion)
Molecules of a gas are free to move. They move
very rapidly and are in constant motion.
19
This is the Eagle Nebula. Its gas dust are
expanding in space.
20
What would happen if this balloon had a hole in
it? What limits the gas?
21
D. Plasma
  • 1. Plasma is - a super-heated, electrically
    charged gas.
  • Plasma is rare on earth.
  • Plasma is extremely energetic dangerous.

22
Examples of plasma - the sun
23
Light bulbs Neon lights
24
Lightning
25
Remember - particles of matter always move.
(Molecular Motion)
  • Solids - particles vibrate in place, tightly
    bound together
  • Liquids - particles are freer, move faster - flow
  • Gases - particles even more free, rapid movement
  • Plasma - very rapid movement, lots of energy

26
Temperature affects particle movement. Heat -
move faster. Cold - move slower.
  • Absolute zero-
  • the temp. at which all molecular motion ceases.
  • - 273o C
  • 0o Kelvin
  • - 459o F

27
This is dry ice (CO2). What happens to it as
the temperature rises? What are its molecules
doing?
28
This is water ice (H2O). What happens to it as
the temperature rises? What are its molecules
doing?
29
II. Gas Behavior
  • A. Measuring Gases
  • 1. - volume can change - gas will fill any
    available space so will be the same volume as
    its container
  • 2. - temperature is the average energy of motion
    of the particles of a substance

30
(3. Temperature)
- The faster the particles are moving, the
greater their energy and the higher the
temperature - A thermometer - a speedometer for
molecules! - Gas molecules at 20o C - travel
at 500 meters per second (typically)
31
4. Pressure
  • Gas particles - constantly move collide with
    each other the walls of their containers.

32
(4. Pressure)
  • This results in an outward push by the gas.
  • This outward force is called pressure.
  • Pressure Force/Area
  • Measured in units of kilopascals(kPa)

33
Objects like a soccer ball or balloon, have gas
under pressure inside that keeps them inflated .
This is a pressurized space suit. - What happens
if any of these get a hole in them?
34
4. Relating Pressure Volume
  • Gases behave in predicable ways.
  • Robert Boyle - English scientist in the 1600s
  • - found that when the pressure of a gas is
    increased at a constant temperature, the volume
    of the gas decreases. When the pressure
    decreases, the volume increases.

35
BOYLES LAW
36
  • Boyles Law also applies to situations where
    volume of a gas changes.
  • Then the pressure also changes.

What would happen to the pressure the volume
if you squeezed one of these balloons in your
hands?
37
5. Relating Pressure Temperature
  • Thought Exercise
  • Think of a sand storm.
  • Would pouring a handful of sand over your arm
    feel different than being in a strong storm?
  • HOW?

38
The greater the speed of the sand particles, the
more energy they carry transfer.
  • Gas particles also travel at great speeds.
  • Remember pressure measures how much gas
    particles push outward on their container.
  • - the greater the speed of the gas
    particles, the greater the pressure.
  • - Temp. is the average speed of particles.

39
Charless Law - 1700s French Scientist Jacques
Charles
  • When the temperature of a gas at a constant
    volume is increased, the pressure of the gas
    increases.
  • When the temperature is decreased, the pressure
    of the gas decreases.

40
Charless Law
41
III. Graphing Gas Behavior
  • Graphs are diagrams that tell how 2 variables or
    factors are related.
  • - graphs can be used to make predictions

42
Collecting data - use a data table
43
Data from a data table can then be graphed.
This graph shows the linear relationship between
temp. volume which are directly proportional.
44
This graph shows the relation- ship between
pressure volume which varies inversely.
45
IV. Changes of State - physical change of matter
from one state or phase to another. (ex. solid -
liquid)
  • A. Energy changes in state
  • 1. A substance changes state when its thermal
    (heat) energy increases or decreases by a
    sufficient amount.
  • 2. Thermal energy - the energy of a
    substances particles
  • - transferred from one substance to another

46
- always flows from a warmer substance to a
cooler substance
  • Remember the arrangement motion of particles
    in a substance determine whether substances are
    solid, liquid, or gas.
  • - particles of solids have the least thermal
    energy, gas the most.

47
B. Changes of State or Phase
  • 1. MELTING - solid to liquid
  • - melting point of a substance is determined
    by how strongly its particles are attracted.
  • - Thermal energy makes molecules vibrate
    faster. At a certain temperature (the melting
    point) they can break free.

48
Melting wax
49
Melting ice - ice begins to melt at 0o C, the
temperature at which molecules are moving fast
enough to flow as a liquid.
50
Molten silver - What happens to the molecules as
the metal cools?
51
Do substances require the same amount of thermal
(heat) energy to melt? THINK of melting - water
ice - steel - plastic - rock
52
2. Freezing - liquid to solid
  • Liquid loses energy as it cools.
  • Molecules slow down.
  • When water reaches 0oC, its molecules are moving
    so slowly that it starts to form into regular
    patterns - ice crystals
  • This is the same temperature at which ice melts!

53
So what does happen to molten silver
molecules as the metal cools?
54
3. Vaporization - liquid to gas
  • Occurs when a liquid gains enough energy to
    become a gas.
  • Two main types
  • - evaporation - molecules on the surface
    escape
  • - ex.s a drying puddle, sweating
  • - boiling -takes place inside a
  • liquid on the surface

55
Note Evaporation happens at the surface
boiling inside the liquid. Boiling is actually
water molecules turning into a bubble of gas
inside the liquid then bubbling out as
densities change. Which requires more energy?
56
- a. boiling point - is the
temperature a which a liquid boils
  • Boiling points of substances
  • - water (at sea level) 100oC
  • - salt 1413o
  • - diamond 4827oC
  • Boiling point is affected by air pressure. The
    lower the air pressure, the less energy is needed
    for molecules to escape. Water will boil at 95oC
    in Denver, Colorado.

57
4. Condensation - gas to liquid
  • Occurs when gas particles lose enough energy to
    become a liquid.
  • - ex.s clouds, mist,breath on a mirror
  • Steam is NOT condensation (water vapor) but tiny
    drops of liquid water suspended in the air.

58
Water vapor condensing on a flower. This
happens when the water vapor touches a cooler
surface loses thermal energy. Think of a cold
glass on a humid day.
59
Fog - water vapor cooling condensing in the
rainforest.
60
5. Sublimation - solid to gas
  • Occurs when the surface particles of a solid gain
    enough energy to become a gas.
  • - particles do NOT pass through a liquid
    state.
  • Ex.s - dry ice, naphthalene(moth balls,) iodine,
    water ice

61
Dry ice - CO2 Note that the fog you see is not
CO2 gas, (you cant see that) - its water vapor
condensing in the cold surrounding the dry ice.
62
Dry ice - CO2
Sublimating - Iodine
63
Water ice snow will also sublimate. How could
this happen? Hint It happens in very cold
places like Antarctica.
64
C. Identifying Substances Through Changes of
States/Phase
  • The properties of substances can help to identify
    them.
  • - boiling/melting points
  • If you were given 3 colorless liquids you could
    identify them by their boiling melting points.

65
  • Freezing - Boiling
  • Water 0o - 100o C
  • Ethanol -117o - 79o
  • Chloroform - 64o - 61o
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