States of Matter Chapter 12. 12.1 - Gases Kinetic molecular theory = describes how gases behave, has 3 major assumptions: Kinetic molecular theory = describes

States of MatterStates of Matter

Chapter 12Chapter 12

12.1 - Gases12.1 - Gases Kinetic molecular theoryKinetic molecular theory = describes how = describes how

gases behave, has 3 major assumptions:gases behave, has 3 major assumptions:

1.1. Particle size = particles are small compared Particle size = particles are small compared to volume of empty space, no forces to volume of empty space, no forces between particlesbetween particles

2.2. Particle motion = particles are in constant Particle motion = particles are in constant motion, move in a straight line until they motion, move in a straight line until they collide with other particles or container collide with other particles or container walls, walls, elastic collisionselastic collisions (no loss of kinetic (no loss of kinetic energy)energy)

12.1…12.1…

3. Particle energy = determined by mass 3. Particle energy = determined by mass and velocity of a particle (KE=1/2 mvand velocity of a particle (KE=1/2 mv22))

In a sample of a gas, all particles have same In a sample of a gas, all particles have same mass but different velocity (so KE of mass but different velocity (so KE of particles varies)particles varies)

TemperatureTemperature = measure of average KE of = measure of average KE of particles in a sample (so at a given temp., all particles in a sample (so at a given temp., all particles have same average KE)particles have same average KE)

12.1 – Gas Behavior12.1 – Gas BehaviorLow density = lots of space between gas Low density = lots of space between gas

particlesparticlesCompression and expansion = empty Compression and expansion = empty

space in a gas container can easily be space in a gas container can easily be pushed into a smaller volume (ex. pushed into a smaller volume (ex. Squishing memory foam)Squishing memory foam)

Diffusion and effusion = random motion of Diffusion and effusion = random motion of gas particles causes them to mix until they gas particles causes them to mix until they are evenly distributedare evenly distributed

12.1 - Diffusion and Effusion12.1 - Diffusion and Effusion DiffusionDiffusion = movement of one material through = movement of one material through

another from area of high concentration to area another from area of high concentration to area of low concentration (ex. Spraying perfume)of low concentration (ex. Spraying perfume)

EffusionEffusion = gas particles escape through a tiny = gas particles escape through a tiny opening (ex. Popping a balloon)opening (ex. Popping a balloon)

At the same temp., heavier particles At the same temp., heavier particles effuse/diffuse slower than lighter ones effuse/diffuse slower than lighter ones (Graham’s law of effusion: rate is inversely (Graham’s law of effusion: rate is inversely proportional to molar mass.proportional to molar mass.

molarmassA

molarmassB

RateB

RateA

Graham’s Law PracticeGraham’s Law Practice

What is the ratio of effusion rates of What is the ratio of effusion rates of krypton and neon at the same temperature krypton and neon at the same temperature and pressure?and pressure?

Graham’s Law PracticeGraham’s Law Practice

What is the molar mass of a gas that takes What is the molar mass of a gas that takes three times longer to effuse than helium?three times longer to effuse than helium?

12.1 – Gas Pressure12.1 – Gas PressurePressurePressure = force exerted by gas particles = force exerted by gas particles

colliding with the walls of the containercolliding with the walls of the containerBarometerBarometer = measures atmospheric = measures atmospheric

pressure, height of mercury determined by pressure, height of mercury determined by gravity exerting downward force on gravity exerting downward force on mercury and upward force of air pressing mercury and upward force of air pressing down on surface of mercury (increase in down on surface of mercury (increase in air pressure = mercury rises, decrease in air pressure = mercury rises, decrease in air pressure = mercury falls), air pressure air pressure = mercury falls), air pressure depends on temp. and humiditydepends on temp. and humidity

12.1 – Units of Pressure12.1 – Units of Pressure

Pascal (Pa)Pascal (Pa) = SI unit of pressure = SI unit of pressureAverage air pressure at sea level =Average air pressure at sea level =

760 mm Hg760 mm Hg760 torr760 torr101.3 kilopascals (kPa)101.3 kilopascals (kPa)14.7 psi14.7 psiOne atmosphere (1 atm)One atmosphere (1 atm)

Table on pg 407Table on pg 407

Pressure conversionsPressure conversions

Convert 350 mmHg to kPaConvert 350 mmHg to kPa

Convert 525 torr to atmospheresConvert 525 torr to atmospheres

Pressure Demos!Pressure Demos!

How to get an egg inside a milk bottle How to get an egg inside a milk bottle (vacuum inside the bottle)(vacuum inside the bottle)

How to make a film canister explode How to make a film canister explode (vacuum outside the canister)(vacuum outside the canister)

Extreme Shaving CreamExtreme Shaving CreamMonster MarshmallowsMonster Marshmallows

12.1 – Dalton’s Law of Partial 12.1 – Dalton’s Law of Partial PressuresPressures

Dalton’s Law of Partial PressuresDalton’s Law of Partial Pressures = total = total pressure of a mixture of gases is equal to the pressure of a mixture of gases is equal to the sum of the pressures of all gases in the sum of the pressures of all gases in the mixturemixturePortion of the total pressure contributed by one Portion of the total pressure contributed by one

gas is called its partial pressuregas is called its partial pressurePartial pressure of a gas depends on the number Partial pressure of a gas depends on the number

of moles of gas, size of the container, and temp.of moles of gas, size of the container, and temp.

Dalton’s Law of partial Dalton’s Law of partial pressurespressures

ntotal PPPPP ...321

Dalton’s law practiceDalton’s law practice

What is the total gas pressure in a sealed What is the total gas pressure in a sealed flask that contains oxygen at a partial flask that contains oxygen at a partial pressure of 0.41 atm and water vapor at a pressure of 0.41 atm and water vapor at a partial pressure of 0.58 atm?partial pressure of 0.58 atm?

12.2 – Forces of Attraction12.2 – Forces of Attraction

Intramolecular forcesIntramolecular forces = attractive forces = attractive forces that hold particles together (bonds)that hold particles together (bonds)

Intermolecular forcesIntermolecular forces = attractive forces = attractive forces between particlesbetween particles

12.2 – Intermolecular Forces12.2 – Intermolecular Forces

Dispersion forcesDispersion forces = weak force between = weak force between two non-polar molecules (those with two non-polar molecules (those with evenly distributed electrons)evenly distributed electrons)Electrons always moving, electron clouds of Electrons always moving, electron clouds of

non-polar molecules repel each othernon-polar molecules repel each otherElectron density around the nucleus shifts so Electron density around the nucleus shifts so

one side of the molecule is more negative one side of the molecule is more negative than the otherthan the other

Leads to weak attraction between these Leads to weak attraction between these temporary dipolestemporary dipoles

12.2 – Dispersion Forces12.2 – Dispersion Forces

12.2 – Intermolecular Forces…12.2 – Intermolecular Forces…

Dipole-Dipole forcesDipole-Dipole forces = forces between = forces between oppositely charged regions of polar oppositely charged regions of polar molecules (permanent dipoles)molecules (permanent dipoles)Ex. HClEx. HClPartially positive H in one molecule of HCl lines Partially positive H in one molecule of HCl lines

up with partially negative Cl in another molecule up with partially negative Cl in another molecule

12.2 – Intermolecular Forces…12.2 – Intermolecular Forces…

Hydrogen bondsHydrogen bonds = a type of dipole-dipole = a type of dipole-dipole attraction between molecules that contain attraction between molecules that contain hydrogen and a highly electronegative hydrogen and a highly electronegative atom with at least one lone pairatom with at least one lone pairExplains why water is a liquid at room Explains why water is a liquid at room

temperature and not a gas temperature and not a gas life on Earth! life on Earth!Hydrogen atom has large partial positive Hydrogen atom has large partial positive

charge and is attracted to oxygen’s large charge and is attracted to oxygen’s large partial negative charge on another moleculepartial negative charge on another molecule

12.2 – Hydrogen Bonds12.2 – Hydrogen Bonds

12.3 – Liquids and Solids12.3 – Liquids and Solids

12.3 – Liquids and Solids…12.3 – Liquids and Solids…

Liquids are much denser than gases due Liquids are much denser than gases due to intermolecular forces that hold particles to intermolecular forces that hold particles togethertogether

Liquids cannot be compressed as much as Liquids cannot be compressed as much as gases because particles are already gases because particles are already closely packed togetherclosely packed together

Molecules in a liquidMolecules in a liquid


FluidityFluidity = ability to flow, both gases and = ability to flow, both gases and liquids are considered fluids because they liquids are considered fluids because they can diffuse through one anothercan diffuse through one anotherLiquids are less fluid than gases due to Liquids are less fluid than gases due to

intermolecular forces that slow down their intermolecular forces that slow down their movementmovement

Ex. Water pipe leak vs. natural gas leakEx. Water pipe leak vs. natural gas leak


ViscosityViscosity = resistance of a liquid to flow = resistance of a liquid to flowStronger intermolecular forces Stronger intermolecular forces higher higher

viscosityviscosityBigger molecules Bigger molecules higher viscosity higher viscosityLower temperature Lower temperature higher viscosity higher viscosity

Ex. Motor oil = need less viscous oil in winter to Ex. Motor oil = need less viscous oil in winter to make sure it keeps flowing at low temperatures, make sure it keeps flowing at low temperatures, need more viscous oil in summer to make sure it need more viscous oil in summer to make sure it stays thick enough to lubricate the engine at very stays thick enough to lubricate the engine at very high temperatureshigh temperatures

12.3 – Liquids and Solids12.3 – Liquids and SolidsSurface tensionSurface tension = energy required to = energy required to

increase surface area of a liquid by a increase surface area of a liquid by a given amountgiven amountStronger attractions between particles Stronger attractions between particles

higher surface tensionhigher surface tensionWater has a very high surface tension due to Water has a very high surface tension due to

hydrogen bonding, allows small insects to hydrogen bonding, allows small insects to walk on water, why we need water AND soap walk on water, why we need water AND soap to clean dishes/clothesto clean dishes/clothes

Surface tension of waterSurface tension of waterMagic milkMagic milk


Capillary actionCapillary action = occurs when adhesion = occurs when adhesion to walls of container is greater than to walls of container is greater than cohesion in the liquidcohesion in the liquidAdhesionAdhesion = force of attraction between = force of attraction between

molecules that are differentmolecules that are differentCohesionCohesion = force of attraction between = force of attraction between

identical moleculesidentical moleculesEx. Meniscus in graduated cylinder, Ex. Meniscus in graduated cylinder,

absorbance of paper towels and diapersabsorbance of paper towels and diapers


Solids = not considered to be fluids, very Solids = not considered to be fluids, very ordered, more dense than liquids because ordered, more dense than liquids because particles are more closely packed togetherparticles are more closely packed togetherException = water, solid ice is less dense than Exception = water, solid ice is less dense than

liquid water due to three dimensional structure liquid water due to three dimensional structure of water molecules (ice cubes and glaciers of water molecules (ice cubes and glaciers float, keeps aquatic life alive in the winter)float, keeps aquatic life alive in the winter)

Why ice floats...Why ice floats...

12.3 – Liquids and Solids…12.3 – Liquids and Solids…Crystalline solidsCrystalline solids = atoms, ions, or = atoms, ions, or

molecules arranged in an orderly, molecules arranged in an orderly, geometric, 3-D structuregeometric, 3-D structure Individual pieces are called crystalsIndividual pieces are called crystalsUnit cellUnit cell = smallest part of a crystal retaining = smallest part of a crystal retaining

the crystal shapethe crystal shapeMolecules in solidsMolecules in solids

12.3 – Liquids and Solids12.3 – Liquids and Solids4 types of crystalline solids:4 types of crystalline solids:

Molecular solids = soft, poor conductors of Molecular solids = soft, poor conductors of heat and electricity, low to moderate melting heat and electricity, low to moderate melting pointspoints

Allotropes = 2 different solid forms of the Allotropes = 2 different solid forms of the same element (ex. Carbon as graphite or same element (ex. Carbon as graphite or diamond), very hard, poor conductors, high diamond), very hard, poor conductors, high melting pointsmelting points

Ionic solids = hard, brittle, poor conductors, Ionic solids = hard, brittle, poor conductors, high melting pointshigh melting points

Metallic solids = soft to hard, excellent Metallic solids = soft to hard, excellent conductors, low to high melting points conductors, low to high melting points


Amorphous solidsAmorphous solids = do not contain = do not contain crystals, no repeating pattern, form when a crystals, no repeating pattern, form when a molten material cools too quicklymolten material cools too quicklyEx. Glass, rubber, plasticsEx. Glass, rubber, plastics

12.4 – Phase Changes12.4 – Phase Changes

Intro to phase changesIntro to phase changes


Why do substances melt?Why do substances melt?As molecules are heated, they gain enough As molecules are heated, they gain enough

KE to overcome attractive forces that hold KE to overcome attractive forces that hold them together as a solidthem together as a solid

Melting pointMelting point = temperature at which forces = temperature at which forces holding crystal lattice together are broken and holding crystal lattice together are broken and solid becomes liquidsolid becomes liquid

REQUIRES energyREQUIRES energy


Why do substances freeze?Why do substances freeze?As heat is removed, molecules lose KE and As heat is removed, molecules lose KE and

slow downslow downFreezing pointFreezing point = temperature at which a liquid = temperature at which a liquid

is converted into a crystalline solidis converted into a crystalline solidRELEASES energyRELEASES energy


Why do liquids become gases?Why do liquids become gases?When energy is added to a liquid, the When energy is added to a liquid, the

temperature increases and molecules gain KE temperature increases and molecules gain KE and escape the liquidand escape the liquid

VaporizationVaporization = process by which a liquid = process by which a liquid changes to a gas or vaporchanges to a gas or vapor

EvaporationEvaporation = vaporization that occurs on the = vaporization that occurs on the surface of a liquid that is not boilingsurface of a liquid that is not boiling

REQUIRES energyREQUIRES energy

12.4 – Phase Changes…12.4 – Phase Changes…

Vapor pressureVapor pressure = pressure exerted by a = pressure exerted by a vapor over a liquidvapor over a liquid

Boiling pointBoiling point = temperature at which vapor = temperature at which vapor pressure of a liquid is equal to pressure of a liquid is equal to atmospheric pressure, molecules atmospheric pressure, molecules throughout the liquid have enough energy throughout the liquid have enough energy to vaporize and bubbles of vapor rise to to vaporize and bubbles of vapor rise to the surfacethe surface

Water boiling in a vacuum Demo!Water boiling in a vacuum Demo!


Why do gases become liquids?Why do gases become liquids?When a vapor molecule loses energy, it slows When a vapor molecule loses energy, it slows

down and is more likely to collide with another down and is more likely to collide with another molecule and bond, releasing energy and molecule and bond, releasing energy and becoming a liquidbecoming a liquid

CondensationCondensation = Process by which a gas or = Process by which a gas or vapor becomes a liquidvapor becomes a liquid

RELEASES energyRELEASES energyEvaporation and CondensationEvaporation and Condensation


What happens when we sweat?What happens when we sweat?Water molecules in sweat gain energy from Water molecules in sweat gain energy from

heat coming off the bodyheat coming off the bodySome molecules gain enough energy to Some molecules gain enough energy to

evaporate, taking energy with themevaporate, taking energy with themMolecules left behind have less energy and Molecules left behind have less energy and

therefore, a lower temperaturetherefore, a lower temperature


SublimationSublimation = solid changes directly to a = solid changes directly to a gas without passing through the liquid gas without passing through the liquid phasephaseEx. Dry iceEx. Dry iceREQUIRES energyREQUIRES energy

DepositionDeposition = gas or vapor changes directly = gas or vapor changes directly to a solid without passing through the to a solid without passing through the liquid phaseliquid phase


Phase diagram = Pressure vs. Phase diagram = Pressure vs. Temperature, shows relationship between Temperature, shows relationship between pressure/temperature/phase of a pressure/temperature/phase of a substancesubstanceTriple pointTriple point = point on the diagram that shows = point on the diagram that shows

the temp. and pressure at which all three the temp. and pressure at which all three phases can exist in equilibrium with eachotherphases can exist in equilibrium with eachother

Critical point = point on the diagram that Critical point = point on the diagram that shows the temp. and pressure at which water shows the temp. and pressure at which water can no longer exist as a liquidcan no longer exist as a liquid

12.4 - Phase Diagram12.4 - Phase Diagram

Documents

States of Matter Chapter 12. 12.1 - Gases Kinetic molecular theory = describes how gases behave, has 3 major assumptions: Kinetic molecular theory = describes