-- shows the relationship among solid, liquid, and gas phases in a graph form.
Tm - normal melting point Tb - normal boiling point
AB - solid-vapor line BC - solid-liquid line
BD - liquid-vapor line
I. Kinetic Theory of Matter
-- theory that explains the effects
of temperature and pressure on matter
A. 3 Postulates
1. All matter is made up of tiny particles.
2. These particles are in constant motion.
3. Collisions between these particles are perfectly elastic.
B. Four States of Matter
1. Solid
2. Liquid
3. Gas
4. Plasma
II. Gases
A. Distinguishing
Properties of Gases
1. Gases have no definite shape and no definite volume. They
take the shape of their container.
2. Particles move very rapidly in gases.
3. Gases have lower densities thatn solids or liquids because the
particles are not as close together.
4. Gases can be compressed because there is alot of space between
the particles.
5. They expand when heated.
B. Gas Pressure
1. A gas exerts a pressure on its container because the gas molecules
are constantly colliding with the walls of the container.
Each collision exerts a force on the walls of the container.
2. Atmospheric pressure is the pressure that the gases in our atmosphere
exert on everything on earth.
Atmospheric pressure is equal to:
a. 101.325 kPa
b. 1 atm
c. 760 mm Hg
d. 760 torr
e. 760 millibars
f. 14.7 lbs/in2
3. Manometer - an instrument used to measure gas pressure.
There are two kinds of manometers:
a. open arm manometer
b. closed arm manometer (also known as a barometer)
4. Converting Units of Pressure
a. 1.5 atm to kPa
1.5 atm|101.325 kPa =
151.95 kPa
| 1 atm
b. 1.5 atm to mm Hg
1.5 atm|760 mm Hg =
1140 mm Hg
| 1 atm
5. Manometer Problems
a. Closed Arm Manometers (barometers)
-- These are easier than open arm problems
First, find the difference in the level of Hg.
Then, convert from mm Hg to kPa.
That's all there is to it.
Example: In a closed manometer, the difference between the two mercury
levels is 105 mm. What is the pressure
of the gas?
105 mm Hg| 101.325 kPa =
14.0 kPa
| 760 mm Hg
b. Open Arm Manometers
-- Because these are open to the atmosphere, you must take atmospheric
pressure into account.
First, find the difference in the level of Hg.
Then, convert from mm Hg to kPa.
Then subtract this from the atmospheric pressure.
Example: An open manometer is filled with mercury. The difference
in the mercury levels in the two arms is
6 mm. What is the total pressure, in kilopascals, of the gas in the
container if the atmospheric
pressure is 101.3 kPa?
6 mm Hg| 101.325 kPa =
0.8 kPa
| 760 mm Hg
101.3 kPa - 0.8 kPa = 100.5 kPa
C. Motion and Physical States
1. Temperature
- a measure of the average kinetic energy of the particles in a substance.
2.
Kinetic Energy - energy an object posses because of its motion.
KE = 1/2 mv2 where m = mass and v = velocity
3. absolute
zero - the temperature at which all molecular motion stops.
Absolute Zero = -273 oC or 0 K
4.
Converting from Celsius to Kelvin
K = oC + 273
5.
Energy always flows from an object of higher temperature to one of lower
temperature until they both reach the same temperature.
6. Heat
is the amount of energy transferred from a warmer object to a cooler object.
Heat is measured in Joules.
III. Distinguishing Properties of Liquids
A. Liquids
have definite volume and definite shape.
B. Particles
slide past one another.
C. Generally
liquids are less dense than solids. (Solid water and Liquid water
are exceptions)
D. Liquids
are less compressible than gases.
E. Liquids
are viscous.
1. Viscosity is the internal friction of a liquid. We also
say that it is the liquid's resistance to flow.
2. High Molecular Weight - High Viscosity
3. Low Molecular Weight - Low Viscosity
F.
Surface Tension - contractive force along the surface of a liquid.
Example: This is why some insects can walk on water.
Example: Soap decreases surface tension.
G. Vapor
Pressure - pressure exerted by the molecules of a
confined vapor
H. Heat
(Enthapy) of Vaporization: total heat or energy required to evaporate
a liquid.
I. Normal
Boiling Point: the temperature at which the vapor pressure is
equal to the standard atmospheric pressure (101.325 kPa).
J. Difference
between Boiling and Evaporation:
1. Evaporation: entirely a suface effect that can occur
at any temperature (liquid to gas)
2. Boiling: bubbles form at the bottom of a liquid and
rise to the top. (liquid to gas) It can only take place at certain
temperatures and pressures.
K. Hydrogen
Bonding in Water
1. Compounds containing hydrogen bonded to N, O, or F are very
polar and form hydrogen bonds.
Hydrogen Bonds are not as strong as an actual chemical bond but
it can hold the two molecules firmly together.
2. Ice is less dense than liquid water. This is because
water expands when it freezes into ice. This occurs because
hydrogen bonding pulls the molecule into an open crytalline structure that
occupies more space than the liquid.
IV. Distinguishing Properties of Solids
A. Solids
have definite volume and definite shape.
B. Particles have
little movement, but they do vibrate against one another.
C. Pure solids
melt at definite temperatures.
D. When solids
melt, a definte amount of heat is absorbed.
E. Melting
Point: temperature at which a solid turns into a liquid.
*** The purity of a substance can be determined by the sharpness and temperature
of its meltin point.
F. Heat
(Enthalpy) of Fusion: total heat or energy required to melt a
substance.
G. All solids
are made of crystals. Crystals have repeating, 3-D patterns.
H. Solids
can form allotropes. Allotropes are two or more different
molecular forms of the same element.
Example: Allotropes of Carbon
Diamond: each carbon atom is covalently bonding to 4 other
carbon atoms to form a network covalent compound.
This is extremely strong.
Graphite: (pencil lead) - carbon atoms are linked together
like a hexagon in layers. These layers can slide over one another.
(very soft) Each time you write with your pencil a layer slides off
onto your paper.
Buckyballs (short for Buckminsterfullerene) - most recently discovered
allotrope of carbon. It has 60 carbons
arranged in pentagons and hexagons. These form a hollow cage
which resembles the dome at EPCOT.
I. Amorphous
Solids: solids which lack crystals. They are not true solids.
examples: plastic, rubber, asphalt, wax, glass.
J. Sublimation:
ability to pass from the solid phase to the gas phase without going through
the liquid phase.
Examples: Solid CO2 (dry ice)
Iodine Crystals
Camphor (used in air fresheners and moth balls)
V. Phase diagrams
-- shows the relationship among solid,
liquid, and gas phases in a graph form.
Tm
- normal melting point
Tb - normal boiling point
AB - solid-vapor
line
BC - solid-liquid line
BD - liquid-vapor
line
triple point: describes when all three states of matter can exist at equilibrium (at the same time)
Phase diagrams are different for every type of substance.
VI. Freezing and Boiling Point Graphs
As you move up the graph from a to e
As you move down the graph from e to a
a - solid is being warmed
e - vapor is cooled
b - solid is melting
d - condensation of vapor
c - liquid is being warmed
c - liquid is cooled
d - liquid is vaporized
b - liquid is freezing
e - vapor is being warmed
a - solid is frozen
VII. The 4th State of Matter -- Plasma
A. Plasma:
gaseous mixture of electrons and positive ions.
B. It
behaves as a gas because it has no definite shape or volume. However,
gases are not made up of electrons and positive ions.
C. In
order for plasma to exist, temperature must be between 50,000 K -
100, 000, 000 K !!!
D. True
Plasma is found in:
1. stars
2. the sun
3. Van Allen radiation belts that surround earth
E. Partial
Plasma (plasma that can exist on earth) is found in:
1. fluorescent lights
2. neon signs
3. lightning bolts
4. flames
F. Aurora
Borealis: also known as the "Northern Lights" is caused by partial
plasma in our atmosphere.