Chapter 16
Solids, Liquids, Gases
Section 1 Kinetic Theory
Pages 476-484
Kinetic Theory of Matter
Page 476
• All matter is composed of small particles
– Atoms, molecules, ions
• These particles are in constant, random
motion
• These particles are constantly colliding with
each other and with the walls of the
container.
Temperature
• Temperature tells how hot or cold an object is
• Temperature is a measure of the average
kinetic energy of the particles of a substance
• Ice molecules are moving slower than
molecules of liquid water which are moving
slower than molecules of steam.
• Absolute zero is the temperature at which no
thermal energy can be removed from an
object.
• - 273 oC also known as 0 K
States of Matter or
Phases of Matter (P477-479)
• Solid
– Has definite shape and volume
– Particles are packed together tightly
– Particles vibrate but are bond together
• Liquid
– Has definite volume but takes the shape of the container.
– Particles are able to move more freely
– Have enough kinetic energy to break the forces that hold them
together and flow.
• Gas
– No definite shape nor definite volume
– Particles are far apart and weak attraction between particles
Phase Change (cont)
Solid/Liquid
– Most substance have a temperature at which it
melts or freezes.
– This is called the melting point.
– At that temperature if the substance looses heat it
freezes and if it gains heat it melts.
– The energy required to melt or freeze a substance
is called the heat of fusion.
Phase Change (P479)
Liquid/Vapor (cont)
– Boiling point is the temperature at which a
substance changes from liquid to vapor or from
vapor to liquid
– Heat of vaporization is the quantity of heat that is
needed to break the attraction between particles
and change a substance from liquid to gas.
– This is also the quantity of heat that must be
removed from a substance to change from vapor
to liquid.
Heating Curve
Water (p480)
Gas (vapor)
140
Boiling
Point
120
Phase Change
100
80
60
Melting
Point
40
20
Phase Change
liquid
0
-20
solid
10
20 30
40 50 60 70
80 90 100 110
Quantity of Heat kJ
Plasma (P480)
• Matter consisting of positively and negatively
charged particles
• Particles are so hot (high kinetic energy) that when
they collide, electrons are knocked loose from the
atoms forming ions (+ and – charged particles).
• Found in stars including the sun
• Most abundant state (phase) in the universe, but
rarely seen on earth.
• Also in lightening bolts, neon and fluorescent lights.
Solid or Liquid (P482& 483)
• Amorphous solids
– Some materials do not change phase at a definite
temperature.
– These materials gradually turn from solid to liquid
over a range of temperatures.
– Lack the highly ordered structure of crystalline solids
– Glass and plastics
• Liquid Crystals
– Do not lose their crystal characteristics as they turn
from solid to liquid.
– Liquid form maintains a crystal structure.
Thermal Expansion (P481)
• Thermal Expansion is an increase in the size of
an object when the temperature increases.
• Kinetic Theory Explanation
– Particles move faster the hotter they are
– Fast moving particles move farther apart
• Thermal Contraction is a decrease in the size
of an object when the temperature decreases
– Particles move slower when cooled
– Slower moving particles move closer together
The Strange Case of Water
Water is unusual, the solid phase is less dense
than the liquid phase. Ice Floats in water.
_
H
H
+
O
+
Chapter 16
Section 2 Properties of Fluids
Read Pages 485-489
Why do Objects Float
• An object will float (in water) if the density of
the object is less than the density of water.
ρ = m/V
m= ρ V
<
Mass of Object
Volume of Object
__________mass of water_________
Volume of water = volume of object
Properties of Fluids (1)
• Archimedes Principle (3rd century BC Greek)
– Buoyancy is the ability of a fluid (liquid or gas) to
exert an upward force on an object immersed in
it.
– The buoyant force on an object is equal to the
weight of the fluid displaced by the object.
– An object will float (in water) if the weight of the
fluid (water) displaced is greater than the weight
of the object.
Pascal’s Principle
• Pressure is force exerted per unit area
• P = Force/Area (N/m2 called a Pascal)
• At any point in a fluid the pressure is equal in
all directions.
• Pascal discovered that pressure applied to a
fluid is transmitted (undiminished, it is the
same) through out the fluid.
Bernoulli’s Principle
• As the velocity of a fluid increases, the
pressure of the fluid decreases.
• This makes the shower curtain blow into the
tub.
• This makes airplanes fly.
Viscosity
• The resistance to flow by a fluid is called
Viscosity.
• Water is low viscosity
• Cold syrup is high viscosity
• “Slow as molasses in January”
• 10W30 motor oil – this is the viscosity.
Chapter 16
Section 3
Behavior of Gases
Read Pages 490-495
• Kinetic Theory
Boyle’s Law
– Particles striking the walls of the container produces
pressure – force against an area of the wall
• Decrease the size of the container then the
particles strike more often
– Increases Pressure
• Increase the size of the container then the
particles strike less often
– Decreases Pressure
• Keeping Temperature and the number of
particles constant.
Charles’s Law P494
• If Pressure is kept constant
• As the temperature rises, particles move
faster and move farther apart.
• As temperature falls, particles move slower
and get closer together.
• As temperature rises, volume rises and as
temperature falls, volume falls.
• V= k T but T must be in Kelvin
• K = oC + 273
Gay-Lussac’s Law
• Pressure-Temperature relationship
• If volume is kept constant and the mass of gas is
kept constant…
• As temperature increases, pressure increases
• As temperature decreases, pressure decreases.
• P= k T
• Temperature must be in kelvin
P =k
T
P1
=
T1
P2
T2