Chapter 3Chapter 3

States of MatterStates of Matter

Kinetic TheoryKinetic Theory

Kinetic means motionKinetic means motion Three main parts of the theoryThree main parts of the theory

All matter is made of tiny particlesAll matter is made of tiny particles These particles are in constant motion and These particles are in constant motion and

the higher the temperature, the faster they the higher the temperature, the faster they movemove

At the same temperature, heavier particles At the same temperature, heavier particles move slower. move slower.

Kinetic TheoryKinetic Theory

are evidence of thisare evidence of this..

Kinetic theory says that molecules are in constant motion.

Perfume molecules moving across the room

A Gas is composed of particlesA Gas is composed of particles usually molecules or atomsusually molecules or atoms Considered to be hard spheres far Considered to be hard spheres far

enough apart that we can ignore their enough apart that we can ignore their volume.volume.

Between the molecules is empty Between the molecules is empty space.space.

The Kinetic Theory of The Kinetic Theory of GasesGasesMakes three assumptions Makes three assumptions about gasesabout gases

The particles are in constant random The particles are in constant random motion.motion.

Move in straight lines until they bounce Move in straight lines until they bounce off each other or the walls.off each other or the walls.

All collisions are perfectly elasticAll collisions are perfectly elastic

The Average speed of an oxygen The Average speed of an oxygen molecule is 1656 km/hr at 20ºCmolecule is 1656 km/hr at 20ºC

The molecules don’t travel very far The molecules don’t travel very far without hitting each other so they without hitting each other so they move in random directions.move in random directions.

Kinetic Energy and Kinetic Energy and TemperatureTemperature

Temperature is a measure of the Temperature is a measure of the AverageAverage kinetic energy of the molecules kinetic energy of the molecules of a substance.of a substance.

Higher temperature faster molecules.Higher temperature faster molecules. At absolute zero (0 K) all molecular At absolute zero (0 K) all molecular

motion would stop.motion would stop.

States of MatterStates of Matter Solid- matter that has a definite shape and volumeSolid- matter that has a definite shape and volume Liquid- matter that flows and has a fixed volumeLiquid- matter that flows and has a fixed volume Gas- matter that takes up both the shape and Gas- matter that takes up both the shape and

volume of a containervolume of a container Vapor- a substance that is currently a gas but Vapor- a substance that is currently a gas but

normally is a liquid or solid at room temperature.normally is a liquid or solid at room temperature. Plasma- matter consisting of a gaseous mixture of Plasma- matter consisting of a gaseous mixture of

electrons and positive ions. Not found on Earthelectrons and positive ions. Not found on Earth

States of MatterStates of Matter

SolidSolid Particles are tightly packedParticles are tightly packed Stuck to each other in a patternStuck to each other in a pattern Vibrate in placeVibrate in place Can’t flowCan’t flow Constant volumeConstant volume

States of MatterStates of Matter

LiquidLiquid Particles are tightly packedParticles are tightly packed Able to slide past each otherAble to slide past each other Can flowCan flow Constant volumeConstant volume

LiquidsLiquids

Spread out on their ownSpread out on their own Fluids- gases and liquids both flowFluids- gases and liquids both flow Viscosity-Viscosity- the resistance to flow the resistance to flow The better the molecules stick to each The better the molecules stick to each

other, the more resistanceother, the more resistance

States of MatterStates of Matter

GasGas Particles are spread outParticles are spread out Flying all over the placeFlying all over the place Can flowCan flow Volume of whateverVolume of whatever

container their incontainer their in

GasesGases

Fill the available spaceFill the available space Particles moving at about 500 m/sParticles moving at about 500 m/s Particles hitting things cause Particles hitting things cause pressurepressure

Matter ChartMatter Chart

Properties:Properties: SolidSolid LiquidLiquid Gas or Gas or VaporVapor

MassMass DefiniteDefinite DefiniteDefinite DefiniteDefinite

ShapeShape DefiniteDefinite IndefiniteIndefinite IndefiniteIndefinite

VolumeVolume DefiniteDefinite DefiniteDefinite IndefiniteIndefinite

Temp. Temp. IncreaseIncrease

Small Small ExpansionExpansion

Moderate Moderate ExpansionExpansion

Large Large ExpansionExpansion

Com- Com-

Pressible?Pressible?

NoNo NoNo YesYes

Law of Conservation of Law of Conservation of MassMass

In all changes, mass cannot be created In all changes, mass cannot be created or destroyedor destroyed

All the mass you start with you end withAll the mass you start with you end with It might be hard to countIt might be hard to count

Law of Conservation of Law of Conservation of EnergyEnergy

In all changes, energy cannot be created In all changes, energy cannot be created or destroyedor destroyed

All the energy you put in, you get outAll the energy you put in, you get out It might be hard to countIt might be hard to count

PressurePressure Pressure is the result of collisions of the Pressure is the result of collisions of the

molecules with the sides of a container.molecules with the sides of a container. Particles in a gas move rapidly in constant Particles in a gas move rapidly in constant

random motion.random motion. They travel in straight paths and move They travel in straight paths and move

independently of each other.independently of each other. As a result, gases fill their containers As a result, gases fill their containers

regardless of the shape and volumeregardless of the shape and volume

Gas PressureGas Pressure

Gas Pressure is the force exerted by a gas Gas Pressure is the force exerted by a gas over an areaover an area

Gas Pressure is the result of simultaneous Gas Pressure is the result of simultaneous collisions of billions of rapidly moving gas collisions of billions of rapidly moving gas particles with an objectparticles with an object

A vacuum is completely empty space - it has A vacuum is completely empty space - it has no pressure.no pressure.

Pressure can be measured with a device called Pressure can be measured with a device called a barometer.a barometer.

BarometerBarometer

At one atmosphere At one atmosphere pressure a column of pressure a column of mercury 760 mm mercury 760 mm high.high.

Dish of Mercury

Column of Mercury

1 atm Pressure

BaromeBarometerter

At one atmosphere At one atmosphere pressure a column of pressure a column of mercury 760 mm mercury 760 mm high.high.

A second unit of A second unit of pressure is pressure is mm Hgmm Hg

1 atm = 760 mm Hg1 atm = 760 mm Hg

760 mm1 atm Pressure

Atmospheric PressureAtmospheric Pressure

Gas pressure you are familiar with is that Gas pressure you are familiar with is that caused by a mixture of gasescaused by a mixture of gases

The AirThe Air Air exerts pressure on the Earth because Air exerts pressure on the Earth because

gravity holds air molecules in Earth’s gravity holds air molecules in Earth’s AtmosphereAtmosphere

Atmospheric Pressure results from the Atmospheric Pressure results from the collisions of air molecules with objects. collisions of air molecules with objects.

Pressure is the Pressure is the amount of force amount of force applied to an area.applied to an area.

PressurePressure

Atmospheric Atmospheric pressure is the pressure is the weight of air per weight of air per unit of area.unit of area.

P =FA

Units for PressureUnits for Pressure

SI Unit is pascal (Pa)SI Unit is pascal (Pa) We measure in kilopascals (kPa)We measure in kilopascals (kPa) Also:Also: Millimeters of mercury (mmHg)Millimeters of mercury (mmHg) Standard atmosphere (atm)Standard atmosphere (atm) 1 atm = 760 mmHg = 101.3 kPa1 atm = 760 mmHg = 101.3 kPa

Standard PressureStandard Pressure

Normal atmospheric pressure at sea Normal atmospheric pressure at sea level.level.

It is equal toIt is equal to 1.00 atm1.00 atm 760 torr (760 mm Hg)760 torr (760 mm Hg) 101.325 kPa101.325 kPa

Conversion ProblemsConversion Problems

1) Tire-pressure gauge records a 1) Tire-pressure gauge records a pressure of 450 kPa. What is the pressure of 450 kPa. What is the measurement expressed inmeasurement expressed in

A) atmospheresA) atmospheres B) millimeters of mercuryB) millimeters of mercury

Conversion Problem #2Conversion Problem #2

What is the pressure in Kilopascals and What is the pressure in Kilopascals and in atmospheres, does a gas exert at 385 in atmospheres, does a gas exert at 385 mm Hg?mm Hg?

Conversion Problem #3Conversion Problem #3

The pressure at the top of Mount Everest The pressure at the top of Mount Everest is 33.7 kPa. Is the pressure greater or is 33.7 kPa. Is the pressure greater or less than 0.25atmless than 0.25atm

Factors Affecting Gas Factors Affecting Gas PressurePressure

Number of ParticlesNumber of Particles VolumeVolume TemperatureTemperature

Number of ParticlesNumber of Particles

Increasing the number of particles will increase Increasing the number of particles will increase the pressure of a gas if the temperature and the pressure of a gas if the temperature and the volume are constantthe volume are constant

Tire is inflated, volume is fairly constantTire is inflated, volume is fairly constant Adding more air will increase the pressureAdding more air will increase the pressure More particles with same volume, greater More particles with same volume, greater

number of collisions number of collisions Greater the pressureGreater the pressure Tire ExplodesTire Explodes

VolumeVolume

Reducing the volume of a gas increases Reducing the volume of a gas increases its pressure if the temperature of the gas its pressure if the temperature of the gas and the number of particles are constant.and the number of particles are constant.

Relationship between volume and Relationship between volume and pressure happens when you breathepressure happens when you breathe

Volume Cont.Volume Cont.

ExampleExample Inhale, diaphragm contractsInhale, diaphragm contracts This causes the chest cavity to expandThis causes the chest cavity to expand Increases the volume, which allows the Increases the volume, which allows the

air particles to expandair particles to expand Leads to a decrease in pressureLeads to a decrease in pressure

Volume Cont.Volume Cont.

Exhale, diaphragm relaxesExhale, diaphragm relaxes Volume of chest cavity decreases Volume of chest cavity decreases Particles in the air squeeze into a smaller Particles in the air squeeze into a smaller

volumevolume Pressure inside your lungs increasesPressure inside your lungs increases

TemperatureTemperature

Raising the temperature of a gas increases the Raising the temperature of a gas increases the pressure if the volume is held constant.pressure if the volume is held constant.

The molecules hit the walls harder.The molecules hit the walls harder. The increase in the number of collisions along with The increase in the number of collisions along with

the increase in force of the collisions causes an the increase in force of the collisions causes an increase in the pressureincrease in the pressure

The only way to increase the temperature at The only way to increase the temperature at constant pressure is to increase the volume.constant pressure is to increase the volume.

Calculating Gas LawsCalculating Gas Laws

Boyle’s LawBoyle’s Law Charles’s LawCharles’s Law Combined Gas LawCombined Gas Law

Boyle’s LawBoyle’s Law At a constant temperature pressure and At a constant temperature pressure and

volume are inversely related.volume are inversely related. As one goes up the other goes downAs one goes up the other goes down P x V = P x V = KK (K is some constant)(K is some constant)

Easier to use PEasier to use P11 x V x V11=P=P22 x V x V22

1 atm

4 Liters

As the As the pressure on a pressure on a gas increasesgas increases

2 atm

2 Liters

As the As the pressure on a pressure on a gas increases gas increases the volume the volume decreasesdecreases

Pressure and Pressure and volume are volume are inversely inversely relatedrelated

P

V

A balloon is filled with 25 L of air at 1.0 A balloon is filled with 25 L of air at 1.0 atm pressure. If the pressure is change atm pressure. If the pressure is change to 1.5 atm what is the new volume?to 1.5 atm what is the new volume?

A balloon is filled with 73 L of air at 1.3 A balloon is filled with 73 L of air at 1.3 atm pressure. What pressure is needed atm pressure. What pressure is needed to change to volume to 43 L?to change to volume to 43 L?

ExamplesExamples

Charles’ LawCharles’ Law

The volume of a gas is directly The volume of a gas is directly proportional to the proportional to the Kelvin Kelvin temperature temperature if the pressure is held constant.if the pressure is held constant.

V = V = K K xx TT (K is some constant)(K is some constant) V/T= V/T= KK VV11/T/T11= V= V22/T/T22

V

T

ExamplesExamples What is the temperature of a gas that is What is the temperature of a gas that is

expanded from 2.5 L at 25ºC to 4.1L at expanded from 2.5 L at 25ºC to 4.1L at constant pressure.constant pressure.

What is the final volume of a gas that What is the final volume of a gas that starts at 8.3 L and 290 K and is heated to starts at 8.3 L and 290 K and is heated to 369 K? 369 K?

Boyle’s & Charles’s Boyle’s & Charles’s ProblemsProblems

1) If I have 45 liters of helium in a balloon at 1) If I have 45 liters of helium in a balloon at 298K and increase the temperature of the 298K and increase the temperature of the balloon to 328K. What will the new volume of balloon to 328K. What will the new volume of the balloon be?the balloon be?

2) My car has an internal volume of 12,000 L. 2) My car has an internal volume of 12,000 L. If I drive my car into the river and it implodes, If I drive my car into the river and it implodes, what will be the volume of the gas when the what will be the volume of the gas when the pressure goes from 1.0 atm to 1.4 atm?pressure goes from 1.0 atm to 1.4 atm?

More ProblemsMore Problems

3) If I have 5.6 L of gas in a piston at a 3) If I have 5.6 L of gas in a piston at a pressure of 151.95 kPa and compress the gas pressure of 151.95 kPa and compress the gas until its volume is 4.8 L, what will the new until its volume is 4.8 L, what will the new pressure inside the piston be?pressure inside the piston be?

4) Oxygen gas is at a temperature of 310K 4) Oxygen gas is at a temperature of 310K when it occupies a volume of 2.3 liters. To when it occupies a volume of 2.3 liters. To what temperature should it be raised to occupy what temperature should it be raised to occupy a volume of 6.5 liters?a volume of 6.5 liters?

Gay Lussac’s LawGay Lussac’s Law The temperature and the pressure of a The temperature and the pressure of a

gas are directly related at constant gas are directly related at constant volume.volume.

P = P = K K xx TT (K is some constant)(K is some constant) P/T= P/T= KK PP11/T/T11= P= P22/T/T22

ExamplesExamples What is the pressure inside a 0.250 L can What is the pressure inside a 0.250 L can

of deodorant that starts at 25ºC and 1.2 of deodorant that starts at 25ºC and 1.2 atm if the temperature is raised to atm if the temperature is raised to 100ºC?100ºC?

At what temperature will the can above At what temperature will the can above have a pressure of 2.2 atm?have a pressure of 2.2 atm?

Putting the pieces Putting the pieces togethertogether

The The Combined Gas LawCombined Gas Law Deals with the Deals with the situation where only the number of situation where only the number of molecules stays constant. molecules stays constant.

(P(P1 1 x Vx V11)/T)/T11= (P= (P2 2 x Vx V22)/T)/T22

Lets us figure out one thing when two of Lets us figure out one thing when two of the others change.the others change.

ExamplesExamples A 15 L cylinder of gas at 4.8 atm A 15 L cylinder of gas at 4.8 atm

pressure at 25ºC is heated to 75ºC and pressure at 25ºC is heated to 75ºC and compressed to 17 atm. What is the new compressed to 17 atm. What is the new volume?volume?

If 6.2 L of gas at 723 mm Hg at 21ºC is If 6.2 L of gas at 723 mm Hg at 21ºC is compressed to 2.2 L at 4117 mm Hg, compressed to 2.2 L at 4117 mm Hg, what is the temperature of the gas?what is the temperature of the gas?

Phase ChangesPhase Changes

Solid

Liquid

Gas

Melting Vaporization

Condensation

Freezing

Liquid

Sublimation

Melting Vaporization

Condensation

Condensation

Solid

Freezing

Gas

EnergyEnergy

The ability change or move matterThe ability change or move matter As you add energy to a liquid, the As you add energy to a liquid, the

temperature goes uptemperature goes up The molecules move fasterThe molecules move faster Eventually they will move fast enough to Eventually they will move fast enough to

break free and become a gasbreak free and become a gas This is This is evaporation- evaporation- the change from a the change from a

liquid to gasliquid to gas

EvaporationEvaporation Molecules at the surface break away Molecules at the surface break away

and become gas.and become gas. Only those with enoughOnly those with enough KE KE

escapeescape Evaporation is a cooling Evaporation is a cooling process.process. It requires heat.It requires heat. Endothermic.Endothermic.

Phases ChangesPhases Changes

If you change rapidly enough, the gas will If you change rapidly enough, the gas will form below the surface an boilform below the surface an boil

Condensation-Condensation- Change from gas to liquid Change from gas to liquid As you cool a gas the molecules slow As you cool a gas the molecules slow

downdown As gas molecules slow down they stick As gas molecules slow down they stick

togethertogether

CondensationCondensationChange from gas to liquidChange from gas to liquidAchieves a dynamic equilibrium with Achieves a dynamic equilibrium with

vaporization in a closed system.vaporization in a closed system.What is a closed system?What is a closed system?A closed system means A closed system means

matter can’t go in or out. matter can’t go in or out. (put a (put a cork in it)cork in it)

What the heck is aWhat the heck is a ““dynamic dynamic equilibrium?equilibrium?””

Phases ChangesPhases Changes

Molecules and atoms don’t change Molecules and atoms don’t change during a phase change during a phase change

the composition doesn’t changethe composition doesn’t change The mass doesn’t changeThe mass doesn’t change The volume does changeThe volume does change Only the attractions and motion changeOnly the attractions and motion change

Solid Liquid Gas

Melt Evaporate

CondenseFreeze