KINETIC THEORY Unit 7 ChemistryLangley *Corresponds to Chapter 13 (pgs. 384-409) in Prentice Hall Chemistry textbook

KINETIC THEORYKINETIC THEORY

Unit 7Unit 7

ChemistryChemistry

LangleyLangley

*Corresponds to Chapter 13 (pgs. 384-409) in Prentice Hall Chemistry textbook


Kinetic Theory states that the tiny Kinetic Theory states that the tiny particles in all forms of matter are in particles in all forms of matter are in constant motion.constant motion. Kinetic refers to motionKinetic refers to motion Helps you understand the behavior of solid, Helps you understand the behavior of solid,

liquid, and gas atoms/molecules as well as liquid, and gas atoms/molecules as well as the physical propertiesthe physical properties

Provides a model behavior based off three Provides a model behavior based off three principalsprincipals


3 Principles of Kinetic Theory3 Principles of Kinetic Theory All matter is made of tiny particles (atoms)All matter is made of tiny particles (atoms) These particles are in constant motionThese particles are in constant motion When particles collide with each other or When particles collide with each other or

the container, the collisions are perfectly the container, the collisions are perfectly elastic (no energy is lost)elastic (no energy is lost)

STATES OF MATTERSTATES OF MATTER

5 States of Matter5 States of Matter SolidSolid LiquidLiquid GasGas PlasmaPlasma Bose-EinsteinBose-Einstein

CondensatesCondensates

http://www.plasmas.org/E-4phases2.jpg

SOLIDSSOLIDS

Particles are tightly packed and close togetherParticles are tightly packed and close together Particles do move but not very muchParticles do move but not very much Definite shape and definite volume (because Definite shape and definite volume (because

particles are packed closely and do not move)particles are packed closely and do not move) Most solids are crystalsMost solids are crystals Crystals are made of unit cells (repeating Crystals are made of unit cells (repeating

patterns)patterns) The shape of a crystal reflects the arrangement of The shape of a crystal reflects the arrangement of

the particles within the solidthe particles within the solid

SOLIDSSOLIDS

Unit cells put together make a crystal Unit cells put together make a crystal lattice (skeleton for the crystal)lattice (skeleton for the crystal)

Crystals are classified into seven crystal Crystals are classified into seven crystal systems: cubic, tetragonal, systems: cubic, tetragonal, orthorhombic, monoclinic, triclinic, orthorhombic, monoclinic, triclinic, hexagonal, rhombohedralhexagonal, rhombohedral

Unit cell Unit cell crystal lattice crystal lattice solid solid

SOLIDSSOLIDS Amorphous Solid:Amorphous Solid:

A solid with no defined shape (not a crystal)A solid with no defined shape (not a crystal) A solid that lacks an ordered internal structureA solid that lacks an ordered internal structure Examples: Clay, PlayDoh, Rubber, Glass, Plastic, Examples: Clay, PlayDoh, Rubber, Glass, Plastic,

AsphaltAsphalt Allotropes:Allotropes:

Solids that appear in more than one formSolids that appear in more than one form 2 or more different molecular forms of the same 2 or more different molecular forms of the same

element in the same physical state (have different element in the same physical state (have different properties)properties)

Example: CarbonExample: Carbon Powder = GraphitePowder = Graphite Pencil “lead” = graphitePencil “lead” = graphite Hard solid = diamondHard solid = diamond

SOLIDSSOLIDS

www.ohsu.edu/research/sbh/resultsimages/crystalvsglass.gif

SOLIDSSOLIDSAllotropes of Carbon: a) diamond, b) graphite, c) lonsdaleite, d)buckminsterfullerene (buckyball), e) C540, f) C70, g) amorphous carbon, and h) single-walled (buckytube)

www.wikipedia.org

LIQUIDSLIQUIDS

Particles are spread apartParticles are spread apart Particles move slowly through a containerParticles move slowly through a container No definite shape but do have a definite No definite shape but do have a definite

volumevolume Flow from one container to anotherFlow from one container to another Viscosity – resistance of a liquid to flowingViscosity – resistance of a liquid to flowing

Honey – high viscosityHoney – high viscosity Water – low viscosityWater – low viscosity

chemed.chem.purdue.edu/.../graphics

GASESGASES

Particles are very far apartParticles are very far apart Particles move very fastParticles move very fast No definite shape and No definite volumeNo definite shape and No definite volume

http://www.phy.cuhk.edu.hk/contextual/heat/tep/trans/kinetic_theory.gif

PLASMAPLASMA

Particles are extremely far apartParticles are extremely far apart Particles move extremely fastParticles move extremely fast Only exists above 3000 degrees CelsiusOnly exists above 3000 degrees Celsius Basically, plasma is a hot gasBasically, plasma is a hot gas When particles collide, they break apart When particles collide, they break apart

into protons, neutrons, and electronsinto protons, neutrons, and electrons Occurs naturally on the sun and starsOccurs naturally on the sun and stars

BOSE-EINSTEIN CONDENSATEBOSE-EINSTEIN CONDENSATE

Particles extremely close togetherParticles extremely close together Particles barely moveParticles barely move Only found at extremely cold Only found at extremely cold

temperaturestemperatures Basically Bose-Einstein is a cold solidBasically Bose-Einstein is a cold solid Lowest energy of the 5 states/phases of Lowest energy of the 5 states/phases of

mattermatter

GASES AND PRESSUREGASES AND PRESSURE

Gas pressure is the force exerted by a gas per unit Gas pressure is the force exerted by a gas per unit surface area of an objectsurface area of an object Force and number of collisionsForce and number of collisions When there are no particles present, no collisions = no When there are no particles present, no collisions = no

pressure = vacuumpressure = vacuum Atmospheric Pressure is caused by a mixuture of gases Atmospheric Pressure is caused by a mixuture of gases

(i.e. the air)(i.e. the air) Results from gravity holding air molecules downward in/on Results from gravity holding air molecules downward in/on

the Earth’s atmosphere; atmospheric pressure decreases the Earth’s atmosphere; atmospheric pressure decreases with altitude, increases with depthwith altitude, increases with depth

Barometers are devices used to measure atmospheric Barometers are devices used to measure atmospheric pressure (contains mercury)pressure (contains mercury)

Standard Pressure is average normal pressure at sea Standard Pressure is average normal pressure at sea levellevel As you go ABOVE sea level, pressure is lessAs you go ABOVE sea level, pressure is less As you go BELOW sea level, pressure is greaterAs you go BELOW sea level, pressure is greater


Standard Pressure Values Standard Pressure Values At sea level the pressure can be recorded as: At sea level the pressure can be recorded as:

14.7 psi (pounds per square inch)14.7 psi (pounds per square inch) 29.9 inHg (inches of Mercury)29.9 inHg (inches of Mercury) 760 mmHg (millimeters of Mercury)760 mmHg (millimeters of Mercury) 760 torr760 torr 1 atm (atmosphere)1 atm (atmosphere) 101.325 kPa (kilopascals)101.325 kPa (kilopascals)

All of these values are EQUAL to each other:All of these values are EQUAL to each other: 29.9 inHg = 101.325 kPa29.9 inHg = 101.325 kPa 760 torr = 760 mmHg760 torr = 760 mmHg 1 atm = 14.7 psi1 atm = 14.7 psi and so on……….and so on……….

Say Say hellohello to Factor Label Method!!!!!!!!!!!! to Factor Label Method!!!!!!!!!!!!


STPSTP Standard Temperature and PressureStandard Temperature and Pressure Standard Pressure values are the values listed on Standard Pressure values are the values listed on

the previous slidesthe previous slides Standard Temperature is 0°C Standard Temperature is 0°C oror 273 K 273 K

If temperature is given to you in Farenheit, must convert If temperature is given to you in Farenheit, must convert first!first!

°F = (9/5)°C + 32°F = (9/5)°C + 32 °C = (5(°F-32)) / 9 Remember order of operation rules°C = (5(°F-32)) / 9 Remember order of operation rules K = 273 + °CK = 273 + °C °C = K – 273°C = K – 273


Pressure ConversionsPressure Conversions Example 1: 421 torr = ? AtmExample 1: 421 torr = ? Atm

Step 1: Write what you knowStep 1: Write what you know Step 2: Draw the fence and place the given in Step 2: Draw the fence and place the given in

the top leftthe top left Step 3: Arrange what you know from step 1 such Step 3: Arrange what you know from step 1 such

that the nondesired units canceling out so that that the nondesired units canceling out so that you are only left with the units you want (i.e. atm)you are only left with the units you want (i.e. atm)

Step 4: SolveStep 4: Solve Step 5: Report final answer taking into account Step 5: Report final answer taking into account

the appropriate significant figuresthe appropriate significant figures


Pressure ConversionsPressure Conversions Example 2: 32.0 psi = ? torrExample 2: 32.0 psi = ? torr

TEMPERATURETEMPERATURE

Temperature is the measure of the average Temperature is the measure of the average kinetic energy of the particles.kinetic energy of the particles.

3 Units for Temperature:3 Units for Temperature: CelsiusCelsius FarenheitFarenheit KelvinKelvin

Has an absolute zeroHas an absolute zero Absolute lowest possible temperatureAbsolute lowest possible temperature All particles would completely stop movingAll particles would completely stop moving

Temperature Conversions:Temperature Conversions: Example 1: Convert 35°C to °FExample 1: Convert 35°C to °F Example 2: Convert 300 Kelvin to °C Example 2: Convert 300 Kelvin to °C

MEASURING PRESSUREMEASURING PRESSURE

Manometers:Manometers: Measure pressureMeasure pressure 2 kinds: open and closed2 kinds: open and closed

Open Manometers:Open Manometers: Compare gas pressure to air pressureCompare gas pressure to air pressure Example: tire gaugeExample: tire gauge

Closed Manometer:Closed Manometer: Directly measure the pressure (no Directly measure the pressure (no

comparison)comparison) Example: barometerExample: barometer

KINETIC ENERGY AND KINETIC ENERGY AND TEMPERATURETEMPERATURE

Energy of motionEnergy of motion Energy of a moving objectEnergy of a moving object Matter is made of particles in motionMatter is made of particles in motion Particles have kinetic energyParticles have kinetic energy KE = (mvKE = (mv22)/2)/2

OROR KE = (ma)/2KE = (ma)/2 Kinetic Energy is measured in Joules Kinetic Energy is measured in Joules

1 J = 1kg1 J = 1kg•m•m22/s/s22

The mass must be in kgThe mass must be in kg The velocity must be in m/s OR acceleration must be in The velocity must be in m/s OR acceleration must be in

mm22/s/s22


Calculate the KE of a car with a mass of Calculate the KE of a car with a mass of 1500 kg and a speed of 50 m/s 1500 kg and a speed of 50 m/s


Calculate the KE of a car with a mass of Calculate the KE of a car with a mass of 6780 grams and a speed of 36 km/h6780 grams and a speed of 36 km/h


Temperature-measure of the average kinetic Temperature-measure of the average kinetic energy of the particles energy of the particles

Kelvin Scale:Kelvin Scale: Has an absolute zero (0K)Has an absolute zero (0K) Absolute lowest possible temperatureAbsolute lowest possible temperature In theory, all particles would completely stop movingIn theory, all particles would completely stop moving

Speed of Gases:Speed of Gases: If two gases have the same temperature (particles If two gases have the same temperature (particles

moving at the same speed) how can you tell which moving at the same speed) how can you tell which gas has a greater speed?gas has a greater speed? The only difference is mass!The only difference is mass! To find mass, use the periodic table To find mass, use the periodic table


Speed of GasesSpeed of Gases Example 1: If CHExample 1: If CH44 and NH and NH33 are both at 284 are both at 284

K, which gas has a greater speed?K, which gas has a greater speed? Step One: Add up the mass of each gas using Step One: Add up the mass of each gas using

the periodic table.the periodic table. Step Two: The lighter gas moves faster (think Step Two: The lighter gas moves faster (think

about a race between a 100-pound man and a about a race between a 100-pound man and a 700-pound man, the lighter man would move 700-pound man, the lighter man would move faster)faster)

Example 2: Which gas has a faster speed Example 2: Which gas has a faster speed between Brbetween Br22 and CO and CO22 if both are at 32°F? if both are at 32°F?

TERMINOLOGY for PHASE TERMINOLOGY for PHASE CHANGESCHANGES

Melting-commonly used to indicate changing Melting-commonly used to indicate changing from solid to liquidfrom solid to liquid Normal melting point-The temperature at which the Normal melting point-The temperature at which the

vapor pressure of the solid and the vapor pressure vapor pressure of the solid and the vapor pressure of the liquid are equalof the liquid are equal

Freezing-Changing from a liquid to a solidFreezing-Changing from a liquid to a solid Melting and freezing occur at the same Melting and freezing occur at the same

temperature temperature Liquifaction-Turning a gas to a liquidLiquifaction-Turning a gas to a liquid

Only happens in low temperature and high pressure Only happens in low temperature and high pressure situationssituations


Difference in Gas and VaporDifference in Gas and Vapor Gas-state of matter that exists at normal room Gas-state of matter that exists at normal room

temperaturetemperature Vaport-produced by particles escaping from a state Vaport-produced by particles escaping from a state

of matter that is normally liquid or solid at room of matter that is normally liquid or solid at room temperaturetemperature

Boiling-used to indicate changing from a liquid Boiling-used to indicate changing from a liquid to a gas/vaporto a gas/vapor Normal boiling point - temperature at which the Normal boiling point - temperature at which the

vapor pressure of the liquid is equal to standard vapor pressure of the liquid is equal to standard atmospheric pressure, which is atmospheric pressure, which is 101.325 kPa101.325 kPa

Boiling point is a function of pressure. Boiling point is a function of pressure. At lower pressures, the boiling point is lower At lower pressures, the boiling point is lower


2 types of boiling: boiling and 2 types of boiling: boiling and evaporationevaporation

Evaporation takes place only at the surface of a Evaporation takes place only at the surface of a liquid or solid while boiling takes place throughout liquid or solid while boiling takes place throughout the body of a liquid the body of a liquid

Particles have high kinetic energyParticles have high kinetic energy Particles escape and become vaporParticles escape and become vapor

Condensation-used to indicate changing Condensation-used to indicate changing from a vapor to a liquidfrom a vapor to a liquid


Sublimation - when a substance changes directly from Sublimation - when a substance changes directly from a solid to a vapora solid to a vapor The best known example is "dry ice", solid COThe best known example is "dry ice", solid CO22

Deposition-when a substance changes directly from a Deposition-when a substance changes directly from a vapor to a solid (opposite of sublimation)vapor to a solid (opposite of sublimation) Example-formation of frostExample-formation of frost

Dynamic equilibriumDynamic equilibrium - w - when a vapor is in equilibrium hen a vapor is in equilibrium with its liquid as one molecule leaves the liquid to with its liquid as one molecule leaves the liquid to become a vapor, another molecule leaves the vapor to become a vapor, another molecule leaves the vapor to become a liquid. An equal number of molecules will be become a liquid. An equal number of molecules will be found moving in both directionsfound moving in both directions Equilibrium - When there is no net change in a systemEquilibrium - When there is no net change in a system


Points to Know:Points to Know: Melting Point-Temperature when solid turns to a Melting Point-Temperature when solid turns to a

liquidliquid Freezing Point-Temperature when liquid turns to a Freezing Point-Temperature when liquid turns to a

solidsolid Boling Point-Temperature when a liquid turns to a Boling Point-Temperature when a liquid turns to a

vaporvapor Doesn’t boil unitl vapor pressure coming off liquid is equal Doesn’t boil unitl vapor pressure coming off liquid is equal

to the air pressure around itto the air pressure around it Since air pressure changes with height, water does not Since air pressure changes with height, water does not

always boil at 100°Calways boil at 100°C Condensing Point-Tempeature when vapor turns to Condensing Point-Tempeature when vapor turns to

liquidliquid

ENTROPYENTROPY

A measure of the disorder of a systemA measure of the disorder of a system Systems tend to go from a state of order (low Systems tend to go from a state of order (low

entropy) to a state of maximum disorder (high entropy) to a state of maximum disorder (high entropy)entropy)

Entropy of a gas is greater than that of a liquid; Entropy of a gas is greater than that of a liquid; entropy of a liquid is greater than that of a solidentropy of a liquid is greater than that of a solid Solids=low entropy; plasma=high entropySolids=low entropy; plasma=high entropy

Entropy tends to increase when temperature Entropy tends to increase when temperature increasesincreases As substances change from one state to another, As substances change from one state to another,

entropy may increase or decreaseentropy may increase or decrease

Le CHATELIER’S PRINCIPLELe CHATELIER’S PRINCIPLE

Anytime stress is placed on a system, the Anytime stress is placed on a system, the sytem will readjust to accommodate that stresssytem will readjust to accommodate that stress

If a chemical system at equilibrium experiences If a chemical system at equilibrium experiences a change in concentration, temperature, a change in concentration, temperature, volume, or total pressure, then the equilibrium volume, or total pressure, then the equilibrium shifts to partially counteract the imposed shifts to partially counteract the imposed changechange

Can be used to predict the effect of a change Can be used to predict the effect of a change in conditions on a chemical equilibriumin conditions on a chemical equilibrium

Is used by chemists in order to manipulate the Is used by chemists in order to manipulate the outcomes of reversible reactions, often to outcomes of reversible reactions, often to increase the yield of reactions increase the yield of reactions


When liquids are heated (stress) they When liquids are heated (stress) they produce vapor particles (adjust)produce vapor particles (adjust)

When liquids are cooled (stress) the When liquids are cooled (stress) the particles inside tighten to form a solid particles inside tighten to form a solid (adjust)(adjust)


Le Chatelier’s Principle explaining boiling and Le Chatelier’s Principle explaining boiling and condensation using covered beaker partially filled with condensation using covered beaker partially filled with waterwater At a given temperature the covered beaker constitutes a At a given temperature the covered beaker constitutes a

system in which the liquid water is in equilibrium with the water system in which the liquid water is in equilibrium with the water vapor that forms above the surface of the liquid. vapor that forms above the surface of the liquid.

While some molecules of liquid are absorbing heat and While some molecules of liquid are absorbing heat and evaporating to become vapor, an equal number of vapor evaporating to become vapor, an equal number of vapor molecules are giving up heat and condensing to become molecules are giving up heat and condensing to become liquid. liquid.

If stress is put on the system by raising the temperature, then If stress is put on the system by raising the temperature, then according to Le Châtelier's principle the rate of evaporation will according to Le Châtelier's principle the rate of evaporation will exceed the rate of condensation until a new equilibrium is exceed the rate of condensation until a new equilibrium is established established

PHASE DIAGRAMSPHASE DIAGRAMS

A diagram showing the conditions at A diagram showing the conditions at which substance exists as a solid, liquid, which substance exists as a solid, liquid, or vaporor vapor

Shows the temperature and pressure Shows the temperature and pressure required for the 3 states of matter to existrequired for the 3 states of matter to exist

Conditions of pressure and temperature Conditions of pressure and temperature at which two phases exist in equilibrium at which two phases exist in equilibrium are indicated on a phase diagram by a are indicated on a phase diagram by a line separating the phasesline separating the phases

Draw the phase diagram for waterDraw the phase diagram for water

PHASE DIAGRAM-WATERPHASE DIAGRAM-WATER

PHASE DIAGRAM-WATERPHASE DIAGRAM-WATER

Explanation of Phase Diagram:Explanation of Phase Diagram: X axis-Temperature (°C)X axis-Temperature (°C) Y axis- Pressure (kPa)Y axis- Pressure (kPa) Line AB – line of sublimationLine AB – line of sublimation Line BD – boiling point lineLine BD – boiling point line Line BC – melting point lineLine BC – melting point line Point B – triple point (all 3 states of matter Point B – triple point (all 3 states of matter

exist at the same time)exist at the same time) TTmm – melting point at standard pressure – melting point at standard pressure TTbb – boiling point at standard pressure – boiling point at standard pressure

HEAT in CHANGES of HEAT in CHANGES of STATESTATE

Energy Diagrams (also referred to as Energy Diagrams (also referred to as Heating Curves)Heating Curves) Graphically describes the enthalpy (the heat Graphically describes the enthalpy (the heat

content of a system at sonstant pressure) content of a system at sonstant pressure) changes that take place during phase changes that take place during phase changeschanges

X axis is Energy (Heat supplied)X axis is Energy (Heat supplied) Y axis is TemperatureY axis is Temperature

HEAT in CHANGES of HEAT in CHANGES of STATESTATE

Constructing Energy DiagramsConstructing Energy Diagrams Step 1: Determine/Identify the melting and boiling Step 1: Determine/Identify the melting and boiling

points for the specified substancepoints for the specified substance Step 2: Draw x and y axis (energy vs temp)Step 2: Draw x and y axis (energy vs temp) Step 3: CalculationsStep 3: Calculations

First diagonal line: Q = mcFirst diagonal line: Q = mcTT First horizontal line: Q = mHFirst horizontal line: Q = mHff

Second diagonal line: Q = mcSecond diagonal line: Q = mcTT Second horizontal line: Q = mHSecond horizontal line: Q = mHvv

Third horizontal line: Q = mcThird horizontal line: Q = mcTT Add up all values!!!Add up all values!!!

Draw the energy diagram for 10 grams of water Draw the energy diagram for 10 grams of water as it goes from –25°C to 140°C as it goes from –25°C to 140°C

Documents

KINETIC THEORY Unit 7 ChemistryLangley *Corresponds to Chapter 13 (pgs. 384-409) in Prentice Hall Chemistry textbook