Kinetic Theory Explains States of Matter

Solids, Liquids, and GasesSolids, Liquids, and Gases
Chapter 16Chapter 16
Section 1 Kinetic TheorySection 1 Kinetic Theory

Solids, Liquids, and GasesSolids, Liquids, and Gases
• Section 1 Kinetic theory slides 3-47Section 1 Kinetic theory slides 3-47
• Section 2 Properties of FluidsSection 2 Properties of Fluids slides 50-64slides 50-64
• Section 3 Behavior of GasesSection 3 Behavior of Gases slides 65-80slides 65-80

1 Kinetic Theory of Matter1 Kinetic Theory of Matter
• Kinetic theoryKinetic theory
• How particles move in the four states ofHow particles move in the four states of
mattermatter
• How particles behave at the melting pointHow particles behave at the melting point
and boiling pointsand boiling points

Kinetic TheoryKinetic Theory
• Explains how particles of matter behaveExplains how particles of matter behave
using three basic assumptions:using three basic assumptions:
– 1) All matter is composed of small particles-1) All matter is composed of small particles-
atoms, molecules and ions.atoms, molecules and ions.

– 2) These particles are in constant motion.2) These particles are in constant motion.
The motion has no pattern.The motion has no pattern.

– 2) These particles are in constant motion.2) These particles are in constant motion.
The motion has no pattern.The motion has no pattern.
– 3) These particles are colliding or crashing3) These particles are colliding or crashing
into each other and into the walls of theinto each other and into the walls of the
container.container.

Thermal EnergyThermal Energy
• Thermal energy is the total energy of theThermal energy is the total energy of the
particles in a material including bothparticles in a material including both
potential and kinetic.potential and kinetic.
• When the temperature is lowered, itsWhen the temperature is lowered, its
particles will have less TE and will vibrateparticles will have less TE and will vibrate
more slowly.more slowly.

Average Kinetic EnergyAverage Kinetic Energy
• Temperature is theTemperature is the
average KE ofaverage KE of
particles in aparticles in a
substance.substance.
• The molecules in aThe molecules in a
solid randomly vibratesolid randomly vibrate
with temperature awith temperature a
measure of theirmeasure of their
average kineticaverage kinetic
energy.energy.

How do solids become liquids?How do solids become liquids?
• Melting pointMelting point is the temperature atis the temperature at
which a solid begins to turn into a liquid.which a solid begins to turn into a liquid.

• Energy is needed for the particles in aEnergy is needed for the particles in a
solid to slip out of their orderedsolid to slip out of their ordered
arrangement.arrangement.

• Energy is needed for the particles in aEnergy is needed for the particles in a
solid to slip out of their orderedsolid to slip out of their ordered
arrangement.arrangement.
• Heat of fusionHeat of fusion is the amount of energyis the amount of energy
needed to change a substance from aneeded to change a substance from a
solid to a liquid at its melting point.solid to a liquid at its melting point.

Why do liquids flow?Why do liquids flow?
• Particles in liquids have more KE allowingParticles in liquids have more KE allowing
them to overcome their attraction and slidethem to overcome their attraction and slide
past each other more readily.past each other more readily.
• This is why liquids flow and take the shapeThis is why liquids flow and take the shape
of their container; however, they still clingof their container; however, they still cling
together and have a definite volume.together and have a definite volume.

What is a gas state?What is a gas state?
• Gas particles have enough KE toGas particles have enough KE to
overcome the attractions among them soovercome the attractions among them so
that they have no fixed volume or shape.that they have no fixed volume or shape.

• They can spread far apart or move closeThey can spread far apart or move close
together to fill a container.together to fill a container.

• They can spread far apart or move closeThey can spread far apart or move close
together to fill a container.together to fill a container.
• If particles in a liquid move fast enoughIf particles in a liquid move fast enough
they can enter the gas state in a processthey can enter the gas state in a process
called vaporization by evaporation orcalled vaporization by evaporation or
boiling.boiling.

How do liquids evaporate?How do liquids evaporate?
• Evaporation is vaporization that occurs atEvaporation is vaporization that occurs at
the surface of a liquid.the surface of a liquid.
• It can occur below the liquid’s boiling pointIt can occur below the liquid’s boiling point
if particles at the surface have enough KEif particles at the surface have enough KE
to escape liquid’s attractive force.to escape liquid’s attractive force.

How does boiling vaporize liquids?How does boiling vaporize liquids?
• Boiling occurs at a specific temperatureBoiling occurs at a specific temperature
which depends on the pressure on thewhich depends on the pressure on the
surface of the liquid.surface of the liquid.

• Boiling occurs at a specific temperatureBoiling occurs at a specific temperature
which depends on the pressure on thewhich depends on the pressure on the
surface of the liquid.surface of the liquid.
• Air exerts pressure on the surface of theAir exerts pressure on the surface of the
liquid which keeps particles from escapingliquid which keeps particles from escaping
the liquid.the liquid.

• TheThe boiling pointboiling point of a liquid is theof a liquid is the
temperature at which the pressure of thetemperature at which the pressure of the
vapor in the liquid is equal to the externalvapor in the liquid is equal to the external
pressure on the surface of the liquid.pressure on the surface of the liquid.

• TheThe boiling pointboiling point of a liquid is theof a liquid is the
temperature at which the pressure of thetemperature at which the pressure of the
vapor in the liquid is equal to the externalvapor in the liquid is equal to the external
pressure on the surface of the liquid.pressure on the surface of the liquid.
• Particles need energy to overcome theParticles need energy to overcome the
force of pressure.force of pressure.

• Heat of vaporizationHeat of vaporization is the amount ofis the amount of
energy needed for the liquid at its boilingenergy needed for the liquid at its boiling
point to become a gas.point to become a gas.

Why do gases fill their containers?Why do gases fill their containers?
• Gas particles move so quickly & are so farGas particles move so quickly & are so far
apart that they overcome the attractiveapart that they overcome the attractive
forces among them; therefore,forces among them; therefore, gases dogases do
not have a definite shape or a definitenot have a definite shape or a definite
volume.volume.

Why do gases fill their containers?Why do gases fill their containers?
• Gas particles move so quickly & are so farGas particles move so quickly & are so far
apart that they overcome the attractiveapart that they overcome the attractive
forces among them; therefore,forces among them; therefore, gases dogases do
not have a definite shape or a definitenot have a definite shape or a definite
volume.volume.
• DiffusionDiffusion is the spreading of particlesis the spreading of particles
throughout a given volume until they arethroughout a given volume until they are
evenly distributed.evenly distributed.

What is the heating curve of aWhat is the heating curve of a
liquid?liquid?

liquid?liquid?
• The graph slopesThe graph slopes
upward when the KEupward when the KE
is rising.is rising.
• At B & D the graph isAt B & D the graph is
a horizontal linea horizontal line
showing watershowing water
temperature does nottemperature does not
change.change.

liquid?liquid?
• At what temp is theAt what temp is the
water turning into awater turning into a
gas?gas?

liquid?liquid?
• At 0At 0°C, ice is melting.°C, ice is melting.

liquid?liquid?
• All of the energy put into ice at this temp isAll of the energy put into ice at this temp is
used to overcome the attractive forcesused to overcome the attractive forces
among the particles in the solid.among the particles in the solid.

liquid?liquid?
• All of the energy put into ice at this temp isAll of the energy put into ice at this temp is
used to overcome the attractive forcesused to overcome the attractive forces
among the particles in the solid.among the particles in the solid.
• After melting, the particles move moreAfter melting, the particles move more
freely and their temp begins to rise.freely and their temp begins to rise.

liquid?liquid?
• At 100At 100°C, water is boiling or vaporizing.°C, water is boiling or vaporizing.

liquid?liquid?
• The temperature stays the same againThe temperature stays the same again
until the attractive forces are overcome.until the attractive forces are overcome.

liquid?liquid?
• The temperature stays the same againThe temperature stays the same again
until the attractive forces are overcome.until the attractive forces are overcome.
• Then energy returns to raising theThen energy returns to raising the
temperatures of the particles.temperatures of the particles.

What is the plasma state?What is the plasma state?
• Much of the matter in the universe isMuch of the matter in the universe is
plasmaplasma, matter made up of positively and, matter made up of positively and
negatively charged particles with annegatively charged particles with an
overall neutral charge.overall neutral charge.

• Much of the matter in the universe isMuch of the matter in the universe is
plasmaplasma, matter made up of positively and, matter made up of positively and
negatively charged particles with annegatively charged particles with an
overall neutral charge.overall neutral charge.
• The faster they move, the greater theThe faster they move, the greater the
force when they collide causing atoms toforce when they collide causing atoms to
rip off.rip off.

• Much of the matter in the universe isMuch of the matter in the universe is plasmaplasma,,
matter made up of positively and negativelymatter made up of positively and negatively
charged particles with an overall neutral charge.charged particles with an overall neutral charge.
• The faster they move, the greater the force whenThe faster they move, the greater the force when
they collide causing atoms to rip off.they collide causing atoms to rip off.
• Ex. Stars, lightning bolts, neon & fluorescentEx. Stars, lightning bolts, neon & fluorescent
bulbs, and auroras.bulbs, and auroras.

Thermal ExpansionThermal Expansion
• Thermal expansionThermal expansion is an increase inis an increase in
the size of a substance when thethe size of a substance when the
temperature is increased.temperature is increased.
• The kinetic theory explains both thermalThe kinetic theory explains both thermal
expansion and contraction that occurs inexpansion and contraction that occurs in
most solids, liquids and gases.most solids, liquids and gases.

How does expansion occur inHow does expansion occur in
solids?solids?
• Expansion joints prevent concrete cracksExpansion joints prevent concrete cracks
when temperatures change.when temperatures change.

liquids?liquids?
• One example of thisOne example of this
occurs in aoccurs in a
thermometer.thermometer.
• The addition ofThe addition of
energy makesenergy makes
particles in the liquidparticles in the liquid
move farther apart.move farther apart.

gases?gases?
• An example is a hotAn example is a hot
air balloon. Heatingair balloon. Heating
the air makes itthe air makes it
expand andexpand and
decreases the densitydecreases the density
making the balloonmaking the balloon
rise.rise.

Why does water behave in differentWhy does water behave in different
ways?ways?
• Water expands whenWater expands when
it freezes due to theit freezes due to the
negative and positivenegative and positive
charges on it.charges on it.

ways?ways?
• Water expands when it freezes due to theWater expands when it freezes due to the
negative and positive charges on it.negative and positive charges on it.
• Unlike charges attract each other. As theUnlike charges attract each other. As the
temp drops, the water particles movetemp drops, the water particles move
closer together lining up so that positivecloser together lining up so that positive
and negative areas are near each otherand negative areas are near each other
leaving empty spaces in the structure.leaving empty spaces in the structure.

ways?ways?
• Water expands when it freezes due to theWater expands when it freezes due to the
negative and positive charges on it.negative and positive charges on it.
• Unlike charges attract each other. As theUnlike charges attract each other. As the
temp drops, the water particles movetemp drops, the water particles move
closer together lining up so that positivecloser together lining up so that positive
and negative areas are near each otherand negative areas are near each other
leaving empty spaces in the structure.leaving empty spaces in the structure.
• Solid ice is less dense than liquid water.Solid ice is less dense than liquid water.

Solid or Liquid?Solid or Liquid?
• Not all materials have a definiteNot all materials have a definite
temperature when they change from solidtemperature when they change from solid
to liquid.to liquid.
• Some get softer and slowly turn to liquidSome get softer and slowly turn to liquid
over a range of temperatures.over a range of temperatures.

Solid or Liquid?Solid or Liquid?
• Not all materials have a definiteNot all materials have a definite
temperature when they change from solidtemperature when they change from solid
to liquid.to liquid.
• Some get softer and slowly turn to liquidSome get softer and slowly turn to liquid
over a range of temperatures.over a range of temperatures.
• TheseThese amorphousamorphous solids, like glass &solids, like glass &
plastic, do not have the ordered structureplastic, do not have the ordered structure
of crystals.of crystals.

Solid or a Liquid?Solid or a Liquid?
• Liquid crystals start to flow in the meltingLiquid crystals start to flow in the melting
phase, but keep their ordered structure.phase, but keep their ordered structure.
• Liquid crystals respond to temperatureLiquid crystals respond to temperature
changes and electric fields.changes and electric fields.
• LCDs are used in watches andLCDs are used in watches and
calculators.calculators.

Solid Liquid Gas
Arrangement:
Closely
packed
together
Arrangement: Arrangement:
Overcome
attractions
Behavior: Behavior: slip
out of
arrangement &
flow
Behavior:

Solid Liquid Gas
Arrangement:
Closely
packed
together
Arrangement:
Cling together
with definite
volume
Arrangement:
Overcome
attractions
Behavior:
Energy is needed
for them to slip
out of
arrangement
Behavior: slip
out of
arrangement &
flow
Behavior: do
not have
definite shape
or volume

2 Properties of Fluids2 Properties of Fluids
• Archimedes’ PrincipleArchimedes’ Principle
• Pascal’s PrinciplePascal’s Principle
• Bernoulli’s PrincipleBernoulli’s Principle

How do ships float?How do ships float?
• BuoyancyBuoyancy is a fluid’s ability to exert anis a fluid’s ability to exert an
upward force on an object in it.upward force on an object in it.

• BuoyancyBuoyancy is a fluid’s ability to exert anis a fluid’s ability to exert an
upward force on an object in it.upward force on an object in it.
• Ships float because the force pushing upShips float because the force pushing up
on the ship is greater than the force of theon the ship is greater than the force of the
ship pushing down.ship pushing down.

• BuoyancyBuoyancy is a fluid’s ability to exert an upwardis a fluid’s ability to exert an upward
force on an object in it.force on an object in it.
• Ships float because the force pushing up on theShips float because the force pushing up on the
ship is greater than the force of the ship pushingship is greater than the force of the ship pushing
down.down.
• If the buoyant force is equal to the object’sIf the buoyant force is equal to the object’s
weight, it floats; if the buoyant force is lessweight, it floats; if the buoyant force is less
than the object’s weight, the object sinks.than the object’s weight, the object sinks.

What is Archimedes’ principle?What is Archimedes’ principle?
• The buoyant force on an object is equal toThe buoyant force on an object is equal to
the weight of the fluid displaced by thethe weight of the fluid displaced by the
object. (displaced or “pushed away”)object. (displaced or “pushed away”)

What is Archimedes’ principle?What is Archimedes’ principle?
• The buoyant force on an object is equal toThe buoyant force on an object is equal to
the weight of the fluid displaced by thethe weight of the fluid displaced by the
object. (displaced or “pushed away”)object. (displaced or “pushed away”)
• A block of wood sinks until it displacesA block of wood sinks until it displaces
enough water to equal its weight, then itenough water to equal its weight, then it
floats.floats.

Do equal-sized objects float?Do equal-sized objects float?
• Would a steel block the same size as theWould a steel block the same size as the
wood block float in water?wood block float in water?

Do equal-sized objects float?Do equal-sized objects float?
• Would a steel blockWould a steel block
the same size as thethe same size as the
wood block float inwood block float in
water?water?
• The volume displacedThe volume displaced
for each block isfor each block is
equal; however, eachequal; however, each
block has a differentblock has a different
mass & a differentmass & a different
densitydensity
•

What does density have to do withWhat does density have to do with
buoyancy?buoyancy?
• If you formed the steel block into the shape of aIf you formed the steel block into the shape of a
boat filled with air, it will float.boat filled with air, it will float.
• The density of the steel boat with air inside isThe density of the steel boat with air inside is
less than the density of the water.less than the density of the water.

Pascal’s PrinciplePascal’s Principle
• PressurePressure is force exerted per unit areais force exerted per unit area
or P= E/A.or P= E/A.
• Blaise Pascal (1623-1662), a FrenchBlaise Pascal (1623-1662), a French
scientist, discovered a useful property ofscientist, discovered a useful property of
fluids.fluids.
• Pressure applied to a fluid is transmittedPressure applied to a fluid is transmitted
or sent throughout the fluid. Ex. Squeezingor sent throughout the fluid. Ex. Squeezing
a toothpaste tube.a toothpaste tube.

How is Pascal’s principle used?How is Pascal’s principle used?
• Hydraulic machinesHydraulic machines
move heavy loadsmove heavy loads
using Pascal’susing Pascal’s
principle. A fluid-filledprinciple. A fluid-filled
pipe connects twopipe connects two
cylinders. Whencylinders. When
pressure is applied topressure is applied to
the smaller one, it isthe smaller one, it is
transferred to thetransferred to the
larger one providinglarger one providing
more force.more force.

Bernoulli’s PrincipleBernoulli’s Principle
• Daniel Bernoulli, a Swiss scientist (1700-1782),Daniel Bernoulli, a Swiss scientist (1700-1782),
discovered that as the velocity of a fluiddiscovered that as the velocity of a fluid
increases, the pressure exerted by the fluidincreases, the pressure exerted by the fluid
decreases.decreases.

Bernoulli’s PrincipleBernoulli’s Principle
• Engineers use this principle when designingEngineers use this principle when designing
aircraft wings and piping systems.aircraft wings and piping systems.

Fluid FlowFluid Flow
• Another property of a fluid is its tendencyAnother property of a fluid is its tendency
to flow.to flow.
• ViscosityViscosity , resistance to flow by a fluid,, resistance to flow by a fluid,
measures how much force is needed formeasures how much force is needed for
one layer of fluid to flow over anotherone layer of fluid to flow over another
layer.layer.

Fluid FlowFluid Flow
• Another property of a fluid is its tendencyAnother property of a fluid is its tendency
to flow.to flow.
• ViscosityViscosity , resistance to flow by a fluid,, resistance to flow by a fluid,
measures how much force is needed formeasures how much force is needed for
one layer of fluid to flow over anotherone layer of fluid to flow over another
layer.layer.
• Water has a low viscosity, but syrup has aWater has a low viscosity, but syrup has a
high viscosity because it flows slowly.high viscosity because it flows slowly.

3 Behavior of Gases3 Behavior of Gases
• How a gas exerts pressure on itsHow a gas exerts pressure on its
containercontainer
• How changing pressure, temperature, orHow changing pressure, temperature, or
volume affect a gasvolume affect a gas

PressurePressure
• According to the kinetic theory, gasAccording to the kinetic theory, gas
particles move constantly bumping intoparticles move constantly bumping into
whatever is in their path.whatever is in their path.
• These collisions result in pressure orThese collisions result in pressure or
amount of force exerted per unit of area.amount of force exerted per unit of area.
• Formula P = F/AFormula P = F/A
• Ex. Balloon, tireEx. Balloon, tire

How is pressure measured?How is pressure measured?
• SI Unit for pressure isSI Unit for pressure is pascal (pa)pascal (pa) = one= one
Newton per square meter or 1 N/mNewton per square meter or 1 N/m22
..

..
• Because this is very small pressure unit,Because this is very small pressure unit,
most pressures are given in kilopascals ormost pressures are given in kilopascals or
kPa.kPa.

..
• Because this is very small pressure unit,Because this is very small pressure unit,
most pressures are given in kilopascals ormost pressures are given in kilopascals or
kPa.kPa.
• Atmospheric pressure at sea level = 101.3Atmospheric pressure at sea level = 101.3
kPa or about weight of large truck /squarekPa or about weight of large truck /square
meter! (decreases with altitude)meter! (decreases with altitude)

Boyle’s LawBoyle’s Law
• If the container gets smaller, whatIf the container gets smaller, what
happens to the pressure?happens to the pressure?

Boyle’s LawBoyle’s Law
• If the container gets smaller, whatIf the container gets smaller, what
happens to the pressure?happens to the pressure?
• Robert Boyle, British scientist (1627-1691)Robert Boyle, British scientist (1627-1691)
If you decrease volume of a container ofIf you decrease volume of a container of
gas & keep the temperature the same, thegas & keep the temperature the same, the
pressure of the gas will increase. If youpressure of the gas will increase. If you
increase the volume & keep temp same,increase the volume & keep temp same,
pressure will decrease.pressure will decrease.

Pressure outside an object affectsPressure outside an object affects
volumevolume
• Weather balloonsWeather balloons
carry instrumentscarry instruments
to high altitudes; asto high altitudes; as
they rise they getthey rise they get
bigger due tobigger due to
decrease indecrease in
atmosphericatmospheric
pressure.pressure.

Using Boyle’s LawUsing Boyle’s Law
• The pressure inside an object multipliedThe pressure inside an object multiplied
by its volume is always equal to the sameby its volume is always equal to the same
number, or a constant, when thenumber, or a constant, when the
temperature stays the same.temperature stays the same.
• PP11VV11= constant = P= constant = P22VV22
• If you know three values, you can find theIf you know three values, you can find the
unknown fourth value.unknown fourth value.

• Use the equation PUse the equation P11VV11 = P= P22VV2.2. Assume thatAssume that
PP11= 101 kPa and V= 101 kPa and V11=10.0 L. If P=10.0 L. If P22= 43.0= 43.0
kPa , what is VkPa , what is V22??

• Use the equation PUse the equation P11VV11 = P= P22VV2.2. Assume thatAssume that
PP11= 101 kPa and V= 101 kPa and V11=10.0 L. If P=10.0 L. If P22= 43.0= 43.0
kPa , what is VkPa , what is V22??
• 101 kPa101 kPa · 10.0 L = 1010 kPaL· 10.0 L = 1010 kPaL
1010 kPaL/43.0 kPa = 24.5 L1010 kPaL/43.0 kPa = 24.5 L

The Pressure-TemperatureThe Pressure-Temperature
RelationshipRelationship
• Have you ever seen “keep away fromHave you ever seen “keep away from
heat” on a spray can? Why?heat” on a spray can? Why?

The Pressure-TemperatureThe Pressure-Temperature
RelationshipRelationship
• Have you ever seen “keep away fromHave you ever seen “keep away from
heat” on a spray can? Why?heat” on a spray can? Why?
• Heat causes the pressure to increaseHeat causes the pressure to increase
since the can is rigid & cannot increase insince the can is rigid & cannot increase in
size until the pressure is too much and thesize until the pressure is too much and the
can explodes. In low temps, decrease incan explodes. In low temps, decrease in
pressure may cause the container topressure may cause the container to
buckle.buckle.

Charles’s LawCharles’s Law
• Jacques Charles, French scientist, 1746-Jacques Charles, French scientist, 1746-
1823, studied gases.1823, studied gases.
• Volume of gas increases with increasingVolume of gas increases with increasing
temperature if pressure remains the sametemperature if pressure remains the same
or volume decreases as temperatureor volume decreases as temperature
decreases.decreases.

• As gas is heated, itsAs gas is heated, its
particles move fasterparticles move faster
& faster & its& faster & its
temperaturetemperature
increases. Instead ofincreases. Instead of
increased pressureincreased pressure
the volume increasesthe volume increases
as it expands theas it expands the
container.container.

• Charles’s LawCharles’s Law
formulaformula
• VV11/T/T11= V= V22/T/T22 whenwhen
pressure keptpressure kept
constantconstant

Kinetic Theory Explains States of Matter

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