Phases of Matter and Phases of Matter and Phase ChangesPhase Changes

PhasePhase

Depends on Depends on strength of forces strength of forces of attraction of attraction between particles.between particles.

..

SolidsSolids Definite shape and volume. Definite shape and volume. Most dense phaseMost dense phase

Difficult to compress.Difficult to compress. Exception is water!.Exception is water!.

Particles vibrate in fixed positionsParticles vibrate in fixed positions Crystalline lattice structure. Crystalline lattice structure. Most attraction between particles.Most attraction between particles.

Note: Note: AmorphousAmorphous solids include glass, solids include glass,

plastic, wax, and silly puttyplastic, wax, and silly putty

LiquidsLiquids

Definite volume Definite volume No definite shapeNo definite shape Hard to compressHard to compress Particles slide past each Particles slide past each

otherother Forces of attraction Forces of attraction

between particles still highbetween particles still high

GasesGases

No definite shape or volumeNo definite shape or volume Expands to fill containerExpands to fill container Lowest densityLowest density

Density depends on pressureDensity depends on pressure

Little attraction between Little attraction between particlesparticles

““Vapor” = a gaseous state of Vapor” = a gaseous state of something that is normally liquid something that is normally liquid (Ex: water vapor)(Ex: water vapor)

Phases AppletPhases Applet Short Summary video on phases: (1 min)Short Summary video on phases: (1 min)

http://www.youtube.com/watch?v=s-KvoVzukHo&safe=active

Applet: (Excellent)Applet: (Excellent)https://phet.colorado.edu/en/simulation/states-://phet.colorado.edu/en/simulation/states-

of-matterof-matter

http://www.harcourtschool.com/activity/http://www.harcourtschool.com/activity/states_of_matter/states_of_matter/

Changes in PhaseChanges in Phase

GasGasCondensationCondensation Vaporization Vaporization

(Boiling or Evaporating)(Boiling or Evaporating)

LiquidLiquidSolidificationSolidification Melting (fusion)Melting (fusion)

SolidSolid

Let’s Skip a PhaseLet’s Skip a Phase SublimationSublimation

Directly from the solid Directly from the solid phase to the gas phase.phase to the gas phase.

Happens with substances Happens with substances with weak intermolecular with weak intermolecular forces of attractionforces of attraction

They separate easily!They separate easily!

Ex: COEx: CO22(s) dry ice, Iodine(s) dry ice, Iodine

COCO22(s) → CO(s) → CO22 (g) (g)http://www.youtube.com/watch?v=8tHOVVgGkpk

EnergyEnergy

EnergyEnergy = capacity to do work or produce heat. = capacity to do work or produce heat. It can be anything that causes matter to move or It can be anything that causes matter to move or change direction.change direction.

Ex: electrical, atomic, mechanical, chemicalEx: electrical, atomic, mechanical, chemical

Law of Conservation of EnergyLaw of Conservation of Energy

Energy can’t be Energy can’t be created or created or destroyed, just destroyed, just transferred from transferred from one form to anotherone form to another

PE vs. KEPE vs. KE

Potential EnergyPotential Energy stored energystored energy

Energy can be stored in Energy can be stored in bonds between atomsbonds between atoms

Kinetic EnergyKinetic Energy energy of motionenergy of motion

All atoms are moving All atoms are moving and vibrating unless at and vibrating unless at absolute zeroabsolute zero

Energy and Changes to Matter Energy and Changes to Matter

Exothermic Change:Exothermic Change: A + B → C + D + energyA + B → C + D + energy

Energy is released or “ex”itsEnergy is released or “ex”its

Endothermic Change:Endothermic Change: A + B + energy → C + DA + B + energy → C + D

Energy is absorbed or “en”tersEnergy is absorbed or “en”ters

Energy During Phase ChangesEnergy During Phase Changes

Solid Liquid, Liquid GasSolid Liquid, Liquid GasEndothermic Endothermic Energy is absorbed and overcomes attractive Energy is absorbed and overcomes attractive

forces between particlesforces between particles

Gas Gas Liquid, Liquid Liquid, Liquid SolidSolidExothermic Exothermic As particles come closer together energy is As particles come closer together energy is

releasedreleased

http://www.kentchemistry.com/links/Matter/HeatingCurve.htm

Heat Energy Heat Energy

Also called Thermal energy, it makes particles Also called Thermal energy, it makes particles move more as it is addedmove more as it is added

Measured in Joules or calories.Measured in Joules or calories.

http://www.youtube.com/watch?v=f1eAOygDP5s&safe=active

Heat Flow Heat Flow Heat energy Heat energy

travels from an travels from an object of higher object of higher temp. to one of temp. to one of lower temp. until lower temp. until both reach the both reach the same temp.same temp.

TemperatureTemperature

Measure of the Measure of the average kinetic energyaverage kinetic energy (motion) of all the particles in a sample.(motion) of all the particles in a sample.

Not a form of energy!!!Not a form of energy!!!But if you add heat energy or take it away, it But if you add heat energy or take it away, it

causes particles to move faster or slower and causes particles to move faster or slower and thus changes the temp.thus changes the temp.

Heat vs. TemperatureHeat vs. Temperature

Teacup vs. BathtubTeacup vs. Bathtub

Both at 25˚CBoth at 25˚C

Which one contains Which one contains more heat energy?more heat energy?

Which one has the Which one has the greater average KE?greater average KE?

Temperature Scales Used in Temperature Scales Used in ChemistryChemistry

CelsiusCelsiusFixed points of scale based on the freezing Fixed points of scale based on the freezing

point and boiling point of waterpoint and boiling point of water0 °C = water freezes, 100 °C = water boils0 °C = water freezes, 100 °C = water boils

KelvinKelvinScale based on lowest temperature possibleScale based on lowest temperature possible

0 K = absolute zero0 K = absolute zero

Temperature Temperature Scales and Scales and

ConversionsConversions

K = ˚C + 273 K = ˚C + 273

Absolute ZeroAbsolute Zero

Temperature at which particles have Temperature at which particles have slowed down so much they no longer slowed down so much they no longer possess any kinetic energy.possess any kinetic energy.

0 Kelvin0 Kelvin

-273° Celsius-273° Celsius

Heating & Cooling CurvesHeating & Cooling Curves

Graphically represents temp. changes as heat Graphically represents temp. changes as heat energy is added or taken away.energy is added or taken away.

Label This GraphLabel This Graph

Interpreting the GraphInterpreting the Graph The slanted portions = The slanted portions =

temp is changingtemp is changing Single phase is heating Single phase is heating

up or cooling downup or cooling down KE is changingKE is changing

The flat portions = The flat portions = temp not changingtemp not changing Substance undergoing Substance undergoing

a phase changea phase change PE is changingPE is changing

Heating Curve for WaterHeating Curve for Water

What is Melting Pt? Boiling Pt?What is Melting Pt? Boiling Pt?

Heat EquationsHeat Equations

Calculates the energy involved when a Calculates the energy involved when a substance changes in temperature or substance changes in temperature or undergoes a phase change.undergoes a phase change.

Physical Constants for WaterPhysical Constants for WaterTable BTable B

Use these constants in Heat EquationsUse these constants in Heat Equations

HHf f = heat of fusion = 334J/g= heat of fusion = 334J/g

HHvv = heat of vaporization = 2260J/g = heat of vaporization = 2260J/g

Specific Heat Capacity (“c”) = 4.18 J/g x KSpecific Heat Capacity (“c”) = 4.18 J/g x K

When temperature of substance changes When temperature of substance changes use this formula:use this formula:

What is Specific Heat Capacity?What is Specific Heat Capacity?

Specific HeatSpecific Heat: “c”: “c”

Joules of heat needed to raise 1 gram of aJoules of heat needed to raise 1 gram of a

substance 1°C.substance 1°C.

Substances have different abilities to absorb Substances have different abilities to absorb heat when energy is applied depending on heat when energy is applied depending on their composition.their composition.

Ex: Piece of Iron vs. Water. Ex: Piece of Iron vs. Water.

When Undergoing Phase Change use one of When Undergoing Phase Change use one of these formulas: these formulas: TEMPERATURE CONSTANTTEMPERATURE CONSTANT

Q = mHfQ = mHf Use when changing from Use when changing from solid to liquid (melting) or solid to liquid (melting) or

liquid to solid (freezing)liquid to solid (freezing)

Q = mHvQ = mHv Use when changing from Use when changing from liquid to gas (vaporization) liquid to gas (vaporization)

or or gas to liquid (condensing)gas to liquid (condensing)

CalorimeterCalorimeter Instrument to determine amount of heat lost or Instrument to determine amount of heat lost or

gained in a reaction by measuring changes in the gained in a reaction by measuring changes in the temp. of water surrounding the system.temp. of water surrounding the system.

Q = mcΔT

Virtual Calorimetryhttp://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/thermochem/heat_metal.html

Try This!!Try This!!

Online App Demonstrates Specific Heat Online App Demonstrates Specific Heat and Calorimetryand Calorimetry

http://elearning.classof1.com/demo/2D_Lab/Chemistry/http://elearning.classof1.com/demo/2D_Lab/Chemistry/specificHeat/specificHeat.htmlspecificHeat/specificHeat.html

Multi-step Heat Problems (Honors)Multi-step Heat Problems (Honors) Need to use more than one of the heat equations and Need to use more than one of the heat equations and

add up the total heat.add up the total heat.Note: Specific Heat of different phases of water!Note: Specific Heat of different phases of water!

HH22O(s) = 2.10 J/gO(s) = 2.10 J/gxx°C°CHH22O (l) = 4.18 J/gO (l) = 4.18 J/gxx°C°CHH22O(g) = 1.84 J/gO(g) = 1.84 J/gxx°C°C

Ex: Calculate the heat energy to raise 10 grams of Ex: Calculate the heat energy to raise 10 grams of water at -25°C to 80°C.water at -25°C to 80°C.Draw a heating curve. Figure out # of steps.Draw a heating curve. Figure out # of steps.1.) Heat ice from -25° to 0°1.) Heat ice from -25° to 0° q = mcq = mcΔΔTT2.) Melt ice to liquid at 0°2.) Melt ice to liquid at 0° q = mHfq = mHf3.) Heat liquid water from 0° to 80° 3.) Heat liquid water from 0° to 80° q = mcq = mcΔΔTT

Heat Lost = Heat Gained (Honors)Heat Lost = Heat Gained (Honors)When two objects of different temperatures When two objects of different temperatures

are placed together in a closed system, are placed together in a closed system, heat flows from hotter to colder object until heat flows from hotter to colder object until they reach same temperature.they reach same temperature.

mcmcΔΔT = mcT = mcΔΔT T

Total heat lost = total heat gainedTotal heat lost = total heat gained