Chapter 13Chapter 13States of MatterStates of Matter

13.1 Gases13.1 GasesThe Kinetic-Molecular TheoryThe Kinetic-Molecular Theory

Explaining the Behavior of GasesExplaining the Behavior of GasesGas PressureGas Pressure

The Kinetic Molecular TheoryThe Kinetic Molecular Theory

Basic AssumptionsBasic AssumptionsParticle SizeParticle Size• Gas particles have no volume (pin point Gas particles have no volume (pin point

particles)particles)• The space between particles is extremely The space between particles is extremely

large compared to the volume of the large compared to the volume of the particles. Due to this distance, there is no particles. Due to this distance, there is no significant attractive or repulsive force significant attractive or repulsive force acting on the particles.acting on the particles.

The Kinetic Molecular TheoryThe Kinetic Molecular Theory

Basic AssumptionBasic Assumption

Particle MotionParticle Motion

• Gas particles are in constant random Gas particles are in constant random motion.motion.

• Collisions between particles are elastic Collisions between particles are elastic (Energy can be transferred from one (Energy can be transferred from one particle to another during a collision, but particle to another during a collision, but no energy is lost when particles collide)no energy is lost when particles collide)

Basic AssumptionsBasic Assumptions

Basic AssumptionsBasic Assumptions

Particle EnergyParticle Energy• The mass and velocity of a particle determine The mass and velocity of a particle determine

the kinetic energy of a particlethe kinetic energy of a particle

• Temperature is a measure of the average Temperature is a measure of the average kinetic energy of particles in a sample.kinetic energy of particles in a sample.

2

2

1mvKE

The Kinetic Molecular TheoryThe Kinetic Molecular Theory

Mass/Velocity Relationship QuestionsMass/Velocity Relationship Questions

Condition #1:Condition #1:

Two particles (one heavy and one light) Two particles (one heavy and one light) traveling at the same velocity.traveling at the same velocity.

Which exhibits the greatest kinetic energy?Which exhibits the greatest kinetic energy?

Condition #2:Condition #2:

Two particles of the same size traveling at Two particles of the same size traveling at different velocities (fast and slow).different velocities (fast and slow).

Which exhibits the greatest kinetic energy?Which exhibits the greatest kinetic energy?

2

2

1mvKE

Explaining the Behavior of GasesExplaining the Behavior of Gases

PropertiesProperties• Low Density Low Density (pinpoint mass/volume of empty (pinpoint mass/volume of empty

space)space)

• Random MotionRandom MotionBehaviorsBehaviorsCompressionCompression

Gases can be Gases can be compressedcompressed due to the large due to the large space that exists between particlesspace that exists between particles

Gases Gases expandexpand to fill their containers due to to fill their containers due to constant random motionconstant random motion

Explaining the Behavior of GasesExplaining the Behavior of Gases

PropertiesProperties• No attractive or repulsive forces acting on No attractive or repulsive forces acting on

particlesparticles• Particles exhibit constant random motionParticles exhibit constant random motion

BehaviorsBehaviors

Particles can flow easily past each other in a Particles can flow easily past each other in a process called process called diffusion. diffusion. The rate of diffusion is The rate of diffusion is dependent on the mass of the particles.dependent on the mass of the particles.

A

B

B

A

molarmass

molarmass

Rate

Rate

Question: Based on this equation which particles diffuse faster, heavy or light particles?

Explaining the Behavior of GasesExplaining the Behavior of Gases

PropertyProperty• Particles exhibit constant random motionParticles exhibit constant random motion

BehaviorBehavior

EffusionEffusion (similar to diffusion, where particles (similar to diffusion, where particles escape through a tiny opening)escape through a tiny opening)

Graham’s Law of EffusionGraham’s Law of Effusion

Rate of effusion Rate of effusion

molarmass

1

Questions/ProblemsQuestions/Problems

1.1. What assumption of the Kinetic-Molecular What assumption of the Kinetic-Molecular Theory explains why a gas can expand to fill a Theory explains why a gas can expand to fill a container?container?

2.2. How does the mass of a particle affect its rate How does the mass of a particle affect its rate of effusion?of effusion?

3.3. Calculate the ratio of diffusion rates for CO and Calculate the ratio of diffusion rates for CO and COCO2.2.

4.4. What is the rate of effusion for a gas that has a What is the rate of effusion for a gas that has a molar mass twice that of a gas that effuses at molar mass twice that of a gas that effuses at a rate of 3.6mol/min?a rate of 3.6mol/min?

Gas PressureGas Pressure

The force that a gas exerts per unit area.The force that a gas exerts per unit area.

Measuring Air Pressure Using a BarometerMeasuring Air Pressure Using a BarometerInvented by Evangelista Torricelli

Two forces affect the height of the mercury column

Gravity and Atmospheric Pressure

A rise in air pressure will cause the height of mercury to rise.

A decrease in air pressure will cause the height of mercury to fall

Pressure and AltitudePressure and Altitude

QuestionQuestion

Which condition would cause the level of Which condition would cause the level of mercury in a barometer to fall below 760 mercury in a barometer to fall below 760 mm?mm?

Being below sea level or being on the top Being below sea level or being on the top of a mountain.of a mountain.

Units of Pressure Units of Pressure The SI unit for pressure is the pascal (Pa)The SI unit for pressure is the pascal (Pa)

At sea level and 0At sea level and 0ooC conditions (STP-C conditions (STP-standard temperature and pressure) a standard temperature and pressure) a barometer will read 760mm Hg. barometer will read 760mm Hg.

Equivalent pressure unitsEquivalent pressure units760 mm Hg = 101.3 kPa = 1atm = 760 torr = 760 mm Hg = 101.3 kPa = 1atm = 760 torr =

14.7 psi14.7 psi

Factor-Label is in the AirFactor-Label is in the Air

Equivalent pressure unitsEquivalent pressure units

760 mm Hg = 101.3 kPa = 1atm = 760 torr = 14.7 psi760 mm Hg = 101.3 kPa = 1atm = 760 torr = 14.7 psi

1.1. Convert 362 torr to kPaConvert 362 torr to kPa

2.2. Convert 35.4 psi to torrConvert 35.4 psi to torr

3.3. Convert 48.9 kPa to psiConvert 48.9 kPa to psi

Dalton’s Law of Partial PressuresDalton’s Law of Partial Pressures

““The total pressure of a mixture of gases is The total pressure of a mixture of gases is equal to the sum of the pressures of all equal to the sum of the pressures of all the gases in a a mixture”the gases in a a mixture”

The partial pressure of a gas is dependent The partial pressure of a gas is dependent on the number of moles of gas, the size of on the number of moles of gas, the size of the container and the temperature of the the container and the temperature of the mixture.mixture.

ntotal PPPPP ......321

Partial Pressure ProblemsPartial Pressure Problems

1. What is the partial pressure of hydrogen gas 1. What is the partial pressure of hydrogen gas in a mixture of hydrogen and helium if the in a mixture of hydrogen and helium if the total pressure is 600 mm Hg and the partial total pressure is 600 mm Hg and the partial pressure of helium is 439 mm Hg?pressure of helium is 439 mm Hg?

2. Find the total pressure in kPa for a mixture 2. Find the total pressure in kPa for a mixture that contains three gases with partial that contains three gases with partial pressures of 122 kPa, 35 psi, and 722 torr.pressures of 122 kPa, 35 psi, and 722 torr.

Chapter 13Chapter 13States of MatterStates of Matter

13.2 Attractive Forces

Dispersion Forces

Dipole-dipole Forces

Hydrogen Bonds

Intramolecular ForcesIntramolecular Forces

Forces that occur between atoms, ions or Forces that occur between atoms, ions or molecules molecules withinwithin a molecule. a molecule.

BondingBonding Attractive PartiesAttractive Parties

IonicIonic Cations and anionsCations and anions

MolecularMolecular Positive nuclei and shared electronsPositive nuclei and shared electrons

MetallicMetallic Metal cations and mobile electronsMetal cations and mobile electrons

Intermolecular ForcesIntermolecular Forces

Forces that occur Forces that occur betweenbetween molecules to molecules to hold them togetherhold them together

DispersionDispersion

Dipole-DipoleDipole-Dipole

Hydrogen BondingHydrogen Bonding

Dispersion ForcesDispersion ForcesWeakWeak forces that occur between non-polar forces that occur between non-polar

molecules that result from a temporary molecules that result from a temporary shift in the density of electrons in electron shift in the density of electrons in electron clouds.clouds.

(Butane)(Butane)

The electrons of two non-polar repulse one The electrons of two non-polar repulse one another which causes the temporary shift.another which causes the temporary shift.

Dispersion ForcesDispersion Forces

With increasing atomic number, the number of With increasing atomic number, the number of electrons in a molecule increases which results electrons in a molecule increases which results in a greater dispersion force. This explains why in a greater dispersion force. This explains why ClCl2 2 is a gas, Bris a gas, Br22 is a liquid and I is a liquid and I22 is a solid. is a solid.

Greater Force = smaller distance between moleculesGreater Force = smaller distance between molecules

Dipole-dipole ForcesDipole-dipole ForcesAttractive force that occurs between molecules that Attractive force that occurs between molecules that have a permanent dipole.have a permanent dipole.

Stronger than dispersion forces as long as the two Stronger than dispersion forces as long as the two molecules have about the same mass.molecules have about the same mass.

Hydrogen BondingHydrogen Bonding

For a hydrogen bond to form, hydrogen For a hydrogen bond to form, hydrogen must be bonded to oxygen, fluorine or must be bonded to oxygen, fluorine or nitrogen.nitrogen.

Attractive Force ReviewAttractive Force Review1.1. Why are dipole-dipole forces typically Why are dipole-dipole forces typically

stronger than dispersion forces?stronger than dispersion forces?

2.2. Which molecules listed below can form Which molecules listed below can form hydrogen bonds? Which ones could only hydrogen bonds? Which ones could only experience dispersion forces (how would experience dispersion forces (how would you know)?you know)?

HH22, NH, NH33, HCl, HF, HCl, HF

3. Predict the relative boiling points of the 3. Predict the relative boiling points of the noble gases.noble gases.

13.3 Liquids and Solids13.3 Liquids and Solids

Liquid BehaviorLiquid Behavior

Density- much denser Density- much denser than gases, not than gases, not compressiblecompressible

FluidityFluidity- diffuse slower - diffuse slower than gases, still “flow”than gases, still “flow”

ViscosityViscosity- measure of - measure of resistance to flowresistance to flow Effect of temperature- Effect of temperature-

higher temp, lower higher temp, lower viscosityviscosity

Liquid BehaviorLiquid Behavior

Surface TensionSurface Tension Causes drops and Causes drops and

meniscusmeniscus

Capillary ActionCapillary Action Water can climb narrow Water can climb narrow

tubestubes

Solid BehaviorSolid Behavior

Density- more dense Density- more dense than gases and liquids than gases and liquids and incompressibleand incompressible

Crystalline SolidsCrystalline Solids Unit Cells – smallest Unit Cells – smallest

particle of a crystal that particle of a crystal that has the same shape as has the same shape as the crystalthe crystal

Crystal StructureCrystal Structure

Types of SolidsTypes of Solids

Molecular Solids-dispersion, dipole, or H-Molecular Solids-dispersion, dipole, or H-bonds (ex: sugar)bonds (ex: sugar)

Covalent Network Solids- covalent bonds Covalent Network Solids- covalent bonds with self (ex: diamond, graphite)with self (ex: diamond, graphite)

Ionic Solids- ionic attraction (ex: salt)Ionic Solids- ionic attraction (ex: salt)

Metallic Solids- mobile electrons (ex: Metallic Solids- mobile electrons (ex: copper)copper)

Amorphous Solids- irregular pattern Amorphous Solids- irregular pattern (ex: glass)(ex: glass)

Phase ChangesPhase Changes

Heating CurveHeating Curve

Endothermic Phase ChangesEndothermic Phase Changes

Melting- solid absorbs Melting- solid absorbs energy until particles energy until particles have enough speed to have enough speed to break free of IM forces break free of IM forces holding them in placeholding them in placeVaporization-liquid Vaporization-liquid absorbs energy until absorbs energy until particles have enough particles have enough speed to break free of speed to break free of IM forces holding them IM forces holding them close togetherclose together

Liquid to GasLiquid to Gas

Evaporation- occurs at surfaceEvaporation- occurs at surfaceBoiling- occurs throughout when vapor pressure equals Boiling- occurs throughout when vapor pressure equals atmospheric pressureatmospheric pressure

Sublimation-solid to gasSublimation-solid to gas

Exothermic Phase ChangesExothermic Phase Changes

CondensationCondensation

DepositionDeposition

FreezingFreezing

Phase DiagramsPhase Diagrams

Triple Point