Matter & Matter & EnergyEnergy

Honors Chemistry Honors Chemistry

ScienceScienceA.A. ScienceScience is a body of knowledge collected by is a body of knowledge collected by

scientists over many years & the methods used scientists over many years & the methods used to obtain the knowledgeto obtain the knowledge

B.B. ChemistryChemistry is the study of the composition, is the study of the composition, structure and properties of matter & the structure and properties of matter & the changes it undergoeschanges it undergoes

ChemicalChemical = any substance that has a definite composition = any substance that has a definite composition

1.1. It is through the analysis of much information on It is through the analysis of much information on matter that we can solve problems & answer matter that we can solve problems & answer questionquestion

2.2. What, how much, how it can be changed, & how fastWhat, how much, how it can be changed, & how fast

States of MatterStates of Matter

melting

freez

ing

condensing

vaporizing

depositionsublimation

Solid

Liquid Gas

VaporizationVaporization Boiling – conversion of a liquid to a gas within the

liquid as well as at its surface Boiling Point – vapor pressure of the liquid equals the

atmospheric pressure Evaporation – particles escape from the surface of

a non-boiling liquid and enter the gas state Particles at the surface have higher than avg energies that

overcome the intermolecular forces that bind them to the liquid

Holt Visual Vaporization and

Condensation

StateState ShapeShape VolumeVolume MovemeMovementnt StructureStructure

Solid Solid

LiquidLiquid

GasGas

Definite

Definite

DefiniteParticles only vibrate about fixed points

Particles packed together in

relatively fixed positions;

strong attractive forces

IndefiniteParticles can

move past one another

Particles move more rapidly –

temporarilyovercome strongattractive forces;

allows flow

IndefiniteIndefiniteParticles move very

rapidly

Particles are ata great distancefrom each other; attractive forces

weak

Intermolecular ForcesIntermolecular Forces

Liquid NitrogenLiquid Nitrogen Boils at -196Boils at -196CC

Mercury Mercury Liquid at room tempLiquid at room temp Freezes at -39Freezes at -39CC

Transfer of Heat from Hg to Transfer of Heat from Hg to NN22

PropertiesProperties

1.1. PhysicalPhysical property - can be observed property - can be observed without changing the identity of the without changing the identity of the substancesubstance

• Intensive is Intensive is independentindependent of amount of amount mp, bp, density, conducts electricity/heat, tempmp, bp, density, conducts electricity/heat, temp

• Extensive is Extensive is dependentdependent of amount of amount mass, volume, amount of energy, heatmass, volume, amount of energy, heat

2.2. ChemicalChemical property – relates to a property – relates to a substance’s ability to undergo substance’s ability to undergo changes that transform it into changes that transform it into different substancesdifferent substances

Changes Changes 1.1. PhysicalPhysical – does not involve a change – does not involve a change

in the identity of a substance; may in the identity of a substance; may change the appearancechange the appearance

2.2. ChemicalChemical – one or more substances – one or more substances are converted into different are converted into different substances with different propertiessubstances with different properties

Alters identity of substance. Produces a Alters identity of substance. Produces a new substancenew substance

The new substance (product) has different The new substance (product) has different properties than the beginning materials properties than the beginning materials (reactants).(reactants).

Signs of a Chemical ChangeSigns of a Chemical Change

1.1. ColorColor

2.2. Gas (change in odor)Gas (change in odor)

3.3. PrecipitatePrecipitate

4.4. Change in temperature (may Change in temperature (may include light)include light)

Endothermic vs. Exothermic reactionsEndothermic vs. Exothermic reactions Note: all chemical and physical Note: all chemical and physical

changes involve energychanges involve energy

What is the 3What is the 3rdrd change? change?

3.3. NuclearNuclear Change - changes the Change - changes the composition of the atom’s nucleus composition of the atom’s nucleus

tremendous amount of energy tremendous amount of energy involvedinvolved

Fission vs. FusionFission vs. Fusion Radioactive decay Radioactive decay Where is uranium? Where is uranium?

GroundGround Refined for nuclear power plantsRefined for nuclear power plants

Radioactive DecayRadioactive Decay

Conservation Matter Conservation Matter and Energyand Energy

Cannot be created or destroyed, only changes form in a chemical or physical change Burning magnesium

• Burn Mg – heavier product, why?

• Mg + O2 MgO

Types of Energy: electrical, mechanical, light, chemical mechanical, thermal• Heater – electrical energy to heat energy• Photosynthesis – light to chemical• Transportation – chemical to thermal to

mechanical

E. ClassificationE. ClassificationMATTER

Anything that has mass and volume

Pure Substances

Fixed composition; characteristic chemical

& phys properties

MixturesBlend of 2/more kinds

of matter, each of which retains its own identity & properties

ElementsPeriodic table;

smallest particle to retain all

properties - atom

Compounds

2/more different elements

chemically bonded (I or C)H2O vs H2O2

Homogeneous(Solution)Uniform in

composition - same

proportion of components throughout

Heterogeneous

Not uniform throughout

The Periodic TableThe Periodic Table

MetalsMetals Location: to the Location: to the leftleft of the staircase of the staircase At room temp, all are solid except for HgAt room temp, all are solid except for Hg Ductile - Ductile - can be drawn out into thin wirescan be drawn out into thin wires Malleable - Malleable - can be hammered into thin can be hammered into thin

sheetssheets LusterLuster (A.K.A. Shininess) (A.K.A. Shininess) Good conductorsGood conductors of heat and electricity of heat and electricity High densityHigh density High melting pointsHigh melting points Ion formation Ion formation – tend to – tend to loselose electrons electrons

resulting in resulting in positivepositive charges charges

NonmetalsNonmetals

Location: to the Location: to the rightright of the staircase of the staircase At room temperature, they are solids, At room temperature, they are solids,

liquids, or gases.liquids, or gases. Dull Dull – no luster– no luster InsulatorsInsulators of heat and electricity. of heat and electricity. BrittleBrittle - Neither malleable or ductileNeither malleable or ductile Lower bp and mp than metals.Lower bp and mp than metals. Ion formation Ion formation – tend to – tend to gaingain electrons electrons

resulting in resulting in negativenegative charges charges

Metalloids (Semimetals)Metalloids (Semimetals)

Located Located between the metals and between the metals and nonmetals, nonmetals, ALONGALONG the staircase . the staircase .

Have properties of both metals and Have properties of both metals and nonmetals.nonmetals.

There are There are 7 metalloids7 metalloids in the periodic in the periodic table: Boron (B), Silicon (Si), Germanium table: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), & Astatine (At).Tellurium (Te), & Astatine (At).

Check for UnderstandingCheck for Understanding

1.1. List the nonmetals in the 5List the nonmetals in the 5thth period. period. Iodine and XenonIodine and Xenon

2.2. Metalloid(s) in group 5A (15)? Metalloid(s) in group 5A (15)? Arsenic and AntimonyArsenic and Antimony

3.3. Liquid metal? Liquid nonmetal?Liquid metal? Liquid nonmetal? MercuryMercury BromineBromine

4.4. Symbol for the ion in group 6A and Symbol for the ion in group 6A and period 3? period 3?

SS-2-2

CompoundsCompounds

2 or more elements chemically 2 or more elements chemically combined through covalent or ionic combined through covalent or ionic bondingbonding

Examples:Examples: Na and ClNa and Cl2 2 react to form react to form NaClNaCl C and OC and O2 2 react to form - react to form - COCO22

How many atoms in How many atoms in NHNH44ClCl?? How many How many H atoms H atoms (NH(NH44))22SOSO44

How many How many H atoms H atoms in 5 (NHin 5 (NH44))22SOSO44

Solid SolutionsSolid Solutions

AlloysAlloys: : Solid solutions containing two or more Solid solutions containing two or more metals or a metal and a nonmetal metals or a metal and a nonmetal

Advantages of alloys over pure metals: Advantages of alloys over pure metals: Stronger, cheaper, resistant to corrosion, lighter, Stronger, cheaper, resistant to corrosion, lighter,

harderharder

Brass is an alloy of copper and

zinc.

Steel is an alloy of carbon and iron.Stainless steel

contains chromium

Bronze is an alloy of copper

and tin.

A closer look at alloysA closer look at alloysAlloy Metals

Yellow Gold (14 or 18 carat)

Gold, Silver, Copper

Red Gold Gold and Copper

White GoldGold and Palladium

Sterling Silver Silver and Copper

SuspensionsSuspensions are are mixtures of particles that mixtures of particles that settle out if let settle out if let undisturbed. undisturbed.

HeterogeneousHeterogeneous Suspensions can be Suspensions can be

filtered, while solutions filtered, while solutions cannot. cannot.

Blood, aerosols, OJBlood, aerosols, OJ

ColloidsColloids are a type of are a type of mixture whose particles are mixture whose particles are held together through held together through Brownian Motion, the Brownian Motion, the erratic movement of colloid erratic movement of colloid particles. particles.

Colloids cause the Tyndall Colloids cause the Tyndall Effect, or scattered light Effect, or scattered light due to Brownian motion. due to Brownian motion.

Intermediate between Intermediate between homogeneous and homogeneous and heterogeneous heterogeneous

The size of the particles is The size of the particles is smaller than those found in smaller than those found in suspensions and greater suspensions and greater than those found in than those found in solutions. solutions.

Milk, paint, fog , smoke, Milk, paint, fog , smoke, dustdust

ColloidsColloids

Shows the scattering of light by shining lasers of different colors through colloids and water.

The laser beam is visible through the colloid.

Tyndall effect is caused by reflection of light by very small particles in suspension in a transparent medium. It is often seen from the dust in the air when sunlight comes in through a window, or when headlight beams are visible on foggy nights

Separation TechniquesSeparation Techniques

HeterogeneousHeterogeneous Mixtures Mixtures FiltrationFiltration: Pour liquid through filter : Pour liquid through filter

paper to collect solidpaper to collect solid CentrifugeCentrifuge: separates solid-liquid : separates solid-liquid

mixtures mixtures DecantingDecanting

HomogeneousHomogeneous Mixtures Mixtures CrystallizationCrystallization: evaporate liquid and : evaporate liquid and

solid will crystallizesolid will crystallize ChromatographyChromatography – used to separate – used to separate

pigments of ink on a strip of paper.pigments of ink on a strip of paper. Distillation Distillation

Separation TechniquesSeparation Techniques

Distillation - Distillation - separation of a solution based on differences in boiling point

CompoundsCompounds

DecompositionDecomposition – compound breaks down into two – compound breaks down into two or more simpler compounds or elementsor more simpler compounds or elements

Electrolysis - Electrolysis - decomposes a compound with electricity

% Concentration of % Concentration of SolutionsSolutions

SoluteSolute SolventSolvent SolutionSolution

Solute Solute x 100% = % x 100% = % ConcentrationConcentration

SolutionSolution

SaturatedSaturated – soln – soln containing the containing the max amt of solutemax amt of solute

UnsaturatedUnsaturated – soln – soln containing less containing less solute than a sat solute than a sat soln under the soln under the existing conditionsexisting conditions

SupersaturatedSupersaturated – – contains more contains more dissolved solute dissolved solute than a saturated than a saturated solution under the solution under the same conditionssame conditions

Solubility Curves

supersaturated solutionsupersaturated solution(stirred)(stirred)

Solubility Solubility (physical change)(physical change)

Definition: mass of Definition: mass of solute needed to solute needed to make a saturated make a saturated solution at a given solution at a given temperaturetemperature solution equilibrium in solution equilibrium in

a closed systema closed system dissolution ↔ dissolution ↔

crystallizationcrystallization Unit = g solute/100 g Unit = g solute/100 g

HH22OO

Solubility Graph for NaNO3

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

0 10 20 30 40 50 60 70 80 90 100 110

Temperature (deg C)

So

lub

ilit

y (

g/1

00 g

wat

er )

Saturated sol’n

Supersaturated solution

Unsaturated solution

At 20oC, a saturated solution contains how many grams of NaNO3 in 100 g of water?What is the solubility at 70oC?

135 g/100 g water

What kind of solution is formed when 90 g NaNO3 is dissolved in 100 g water at 30oC?

unsaturated

What kind of solution is formed when 120 g NaNO3 is dissolved in 100 g water at 40oC?

supersaturated

90 g

Solubility of Solubility of solidssolids in liquids in liquids

For most solids, increasing For most solids, increasing temperature, increases solubility.temperature, increases solubility.

In general, “like dissolves like”. In general, “like dissolves like”. Depends onDepends on Type of bondingType of bonding Polarity of moleculePolarity of molecule Intermolecular forces between solute Intermolecular forces between solute

and solventand solvent

Solubility of GasesSolubility of Gases Gases are less Gases are less

soluble at high soluble at high temperatures than temperatures than at low temperaturesat low temperatures

Increasing Increasing temperature, temperature, decreases solubility.decreases solubility.

Increasing pressure, Increasing pressure, increases solubility.increases solubility.

The quantity of gas that dissolves in a The quantity of gas that dissolves in a certain volume of liquid is certain volume of liquid is directly directly proportionalproportional to the pressure of the gas to the pressure of the gas (above the solution).(above the solution).

EffervescenceEffervescence – rapid escape of gas – rapid escape of gas dissolved in liquiddissolved in liquid

Factors Affecting SolubilityFactors Affecting Solubility

Increase surface area of solute Increase surface area of solute (crushing)(crushing)

Stir/shakeStir/shake Increase temperatureIncrease temperature

Energy ConceptsEnergy Concepts

ThermochemistryThermochemistry: the study of the : the study of the changes in energy that accompany a changes in energy that accompany a chemical reaction and physical changes. chemical reaction and physical changes.

Chemical Reactions involve changes in Chemical Reactions involve changes in energy that result fromenergy that result from• Bond breakingBond breaking that that requiresrequires energy ( energy (absorbsabsorbs) )

from the surroundings.from the surroundings.• Bond makingBond making that that producesproduces energy ( energy (releasesreleases) to ) to

the surroundings.the surroundings.

Changes in energy result in an energy Changes in energy result in an energy flow or transfer.flow or transfer.

Heat vs. TemperatureHeat vs. Temperature HeatHeat: (: (qq) is the energy ) is the energy

transferred due to transferred due to changes in temperature. changes in temperature.

• TemperatureTemperature (T) is a (T) is a measure of the average measure of the average particle motion or the particle motion or the average kinetic energy. average kinetic energy.

• HeatHeat flows spontaneously flows spontaneously from a higher to a lower from a higher to a lower temperature.temperature.

Heat vs. Temp Simulation - Heat vs. Temp Simulation - EurekaEureka

CalorimeterCalorimeter

Heat is measured in a calorimetercalorimeter. Changes in temperature are measured in a known quantity of water in an insulated vessel.

Simple calorimeter used in class = Styrofoam cup

Types of ReactionsTypes of Reactions1.1. ExothermicExothermic: : releasesreleases heat into their heat into their

surroundings. surroundings. Heat is a Heat is a productproduct and temperature of the and temperature of the

surroundingssurroundings increaseincrease. . This occurs during This occurs during bond formationbond formation..

Exothermic Reaction

(system)

surroundings

surroundings

surroundingssurroundings

Types of ReactionsTypes of Reactions

2.2. EndothermicEndothermic: : absorbsabsorbs heat from the heat from the surroundings.surroundings.

Heat acts as a Heat acts as a reactantreactant and temperature and temperature of the of the surroundingssurroundings decreasesdecreases..

This occurs during This occurs during bond breakingbond breaking..

Endothermic Reaction

(system)

surroundings

surroundings

surroundingssurroundings

Exothermic ExampleExothermic Example::Dissolving calcium chloride in waterDissolving calcium chloride in water

Combustion Combustion reactions arereactions are ALWAYSALWAYS exothermicexothermic: :

CC33HH8 (g)8 (g) + 5O + 5O22 (g)(g) → 3CO → 3CO22 (g)(g) + 4H + 4H22OO(g)(g) + + 2043 kJ2043 kJ

Endothermic ExampleEndothermic Example::2NH2NH44Cl Cl (s)(s) + Ba(OH) + Ba(OH)22·8H·8H22O O (s) (s) + + 63.9 kJ63.9 kJ

BaClBaCl2 (s)2 (s) + 2NH + 2NH3 (g)3 (g) + 10H + 10H22O O (l)(l)

Physical states are written – influences the overall energy Physical states are written – influences the overall energy exchanged. Very specific!exchanged. Very specific!

2H O +2 -12 (s) (aq) (aq)CaCl Ca + 2Cl + 8 8.0kJ

Forms of Energy Forms of Energy Mechanical, Heat, Chemical, Mechanical, Heat, Chemical, Electrical, Radiant, Sound, Electrical, Radiant, Sound,

NuclearNuclear

Changes of StateChanges of StateA.A. EnergyEnergy

1.1. TypesTypesa)a) Potential energyPotential energy is the energy of is the energy of

positionposition

1)1) As particles move apart, the PE As particles move apart, the PE increasesincreases

2)2) The PE of a The PE of a gasgas is is greatergreater than the PE of than the PE of a a liquidliquid which in turn is which in turn is greatergreater than than the PE of a the PE of a solidsolid

3)3) During During condensationcondensation, the PE decreases , the PE decreases and energy is released. This is an and energy is released. This is an exothermicexothermic change. change.

b)b) Kinetic energyKinetic energy is the energy of is the energy of motionmotion..1)1) Except at 0 K, all particles are in Except at 0 K, all particles are in constantconstant

motionmotion2)2) TemperatureTemperature is a measure of the avg KE of is a measure of the avg KE of

the particles in a sample.the particles in a sample.3)3) When temperature is increased, the KE of the When temperature is increased, the KE of the

particles particles increasesincreases..4)4) In a liquid, the particles must have a In a liquid, the particles must have a

minimum KE (Eminimum KE (Emm) in order to overcome the ) in order to overcome the intermolecular attractions of neighboring intermolecular attractions of neighboring particles to escape.particles to escape.

• The stronger the intermolecular forces in a The stronger the intermolecular forces in a liquid, the higher the Eliquid, the higher the Emm..

Changes of StateChanges of State

Heating and Cooling CurvesHeating and Cooling Curvesgraph of temp of a substancegraph of temp of a substance

1.1. Label the Heating Curve of WaterLabel the Heating Curve of Water

2.2. Evaluate the energy changes that occur Evaluate the energy changes that occur during a heating curve.during a heating curve.

• HHff – – heat of fusionheat of fusion: energy needed to melt : energy needed to melt an amount of a substance at its mpan amount of a substance at its mp

• HHvv – – heat of vaporizationheat of vaporization: energy needed : energy needed to vaporize an amount of a substance at its to vaporize an amount of a substance at its bpbp

• HHff and H and Hvv Units Units: J/g or kJ/mol or cal/g: J/g or kJ/mol or cal/g

• HHff and H and Hvv are are physical properties physical properties of a of a substancesubstance

A

BC

DE

Energy

Tem

pera

ture

(ºC

)

0

100

Heating Curve for Water

Solid

Liqu

id

Gas

q= mCΔT

q= mCΔT

q= mCΔT

s lq= mHf

l gq= mHv

C = 2.092 J/g°C

C = 4.184 J/g°C

C = 1.841 J/g°C

Hf = 334 J/g

Hv =2259 J/g

Endo

ther

mi

cq>

0

ProblemsProblems1.1. Calculate the energy (in cal) needed to Calculate the energy (in cal) needed to

melt 125.0 g of ice at 0.0melt 125.0 g of ice at 0.0°C°C

2.2. How much energy (in kJ) is needed to How much energy (in kJ) is needed to warm 180.0g of ice at -20.0°C to water at warm 180.0g of ice at -20.0°C to water at 75.0°C?75.0°C?

3.3. If 275.0 g of liquid water at 100.0°C and If 275.0 g of liquid water at 100.0°C and 475.0 g at 30.0°C of water are mixed in 475.0 g at 30.0°C of water are mixed in an insulated container, what is the final an insulated container, what is the final temperature?temperature?

124.2 kJ

55.7°C

9,978 cal

Physical Properties of Gases:Physical Properties of Gases:

1. Gases consist of small particles that have 1. Gases consist of small particles that have mass. These particles are usually molecules, mass. These particles are usually molecules, except for the noble gases.except for the noble gases.

Physical Properties of Gases:Physical Properties of Gases:2.2. Gases have mass. The density is Gases have mass. The density is

much smaller than solids or liquids, much smaller than solids or liquids, but they have mass. (A full balloon but they have mass. (A full balloon weighs more than an empty one.)weighs more than an empty one.)

3.3. The particles in gases are separated The particles in gases are separated by relatively large distances. Gases by relatively large distances. Gases can be compressed. It is very easy can be compressed. It is very easy to reduce the volume of a gas. to reduce the volume of a gas.

4.4. Unlike liquids, Unlike liquids, gases completely gases completely fill their fill their containers.containers.

5.5. The particles in The particles in gases are in gases are in constant rapid constant rapid motion (random).motion (random).

6.6. Gases can move through each other Gases can move through each other rapidly - diffusion (ex. food smells and rapidly - diffusion (ex. food smells and perfume)perfume)

7. Gases exert pressure because their particles frequently collide with the walls of their container and each other.

8. Collisions of gas particles are elastic.8. Collisions of gas particles are elastic.

Inelastic Collision

Elastic Collision

Gas particles do not slow down when hitting each other or the walls of their container.

9. Gas particles exert no force on one another. Attractive forces are so weak between particles they are assumed to be zero.

10. Temperature of a gas is simply a measure of the average kinetic energy of the gas particles.

High temp. = high KELow temp. = low KE

The pressure of a gas depends upon temperature

high temp. = more collisions, high pressure

low temp. = less collisions, low pressure

Low pressure High pressure

Boyle’s Law Boyle’s Law Pressure - Volume RelationshipPressure - Volume Relationship

The pressure & volume of a sample of gas at The pressure & volume of a sample of gas at constant temperatureconstant temperature are are inverselyinversely proportional proportional to each other. Law assumes n (amount) is to each other. Law assumes n (amount) is constant. constant.

Inverse P1V1 = P2V2

Boyle’s LawBoyle’s Law

V ____P ____ (smaller volume, ____________)more collisions

Boyle’s Law Boyle’s Law ProblemProblem

A sample of oxygen occupies 300. mL A sample of oxygen occupies 300. mL under a pressure of 740. mm Hg. If under a pressure of 740. mm Hg. If the temperature remains constant, the temperature remains constant, calculate the volume under a calculate the volume under a pressure of 750. mmHg.?pressure of 750. mmHg.?

VV11 = 300. mL = 300. mL VV22 = ? = ?

PP11 = 740. mm Hg = 740. mm Hg PP22 = 750. mm Hg = 750. mm Hg

V2 = 296. mL

Charles’ LawCharles’ Law: : Temperature - Volume RelationshipTemperature - Volume Relationship. .

At At constant pressureconstant pressure the volume of a fixed the volume of a fixed amount of gas is amount of gas is directlydirectly proportional to its proportional to its absoluteabsolute temperature. Law assumes n is temperature. Law assumes n is constant.constant.

Direct 1 2

1 2

V V =

T T

*Temperatures must be in Kelvin!

K = °C + 273

Balloon in cool and cold water:Balloon in cool and cold water:

Charles’s LawCharles’s Law

Charles’s Law ProblemCharles’s Law Problem A gas sample at 83ºC occupied a A gas sample at 83ºC occupied a

volume of 1470 mvolume of 1470 m33. At what . At what temperature, in ºC, will it occupy a temperature, in ºC, will it occupy a volume of 1250 mvolume of 1250 m33??

VV11 = 1470 m = 1470 m33 VV22 = 1250 = 1250 mm33

TT11 = 83°C = 356 K = 83°C = 356 K TT22 = ? = ?

T2 = 30.°C

Gay-Lussac’s LawGay-Lussac’s LawPressure-Temperature Pressure-Temperature

RelationshipRelationship The pressure of a fixed volume of The pressure of a fixed volume of

gas is gas is directlydirectly proportional to its proportional to its absoluteabsolute temperature. Law assumes temperature. Law assumes n is constant.n is constant. Direct

P1 = P2

T1 T2 *Temperatures must be in Kelvin!

K = °C + 273

Gay-Lussac’s LawGay-Lussac’s Law

T ____ P ____ (moves faster,) more collisions

Gay-Lussac’s Law ProblemGay-Lussac’s Law Problem

Before a trip, the pressure in a car tire was Before a trip, the pressure in a car tire was 1.80 atm at 211.80 atm at 21ooC. At the end of the trip, C. At the end of the trip, the pressure gauge reads 1.90 atm. the pressure gauge reads 1.90 atm. Calculate the temperature, in Celsius, of Calculate the temperature, in Celsius, of the air inside the tire at the end of the the air inside the tire at the end of the trip. Assume the tire volume does not trip. Assume the tire volume does not change. change.

PP11 = 1.80 atm = 1.80 atm PP22 = 1.90 = 1.90 atmatm

TT11 = 21°C = 294 K = 21°C = 294 K TT22 = ? = ?T2 = 37°C

The Combined Gas Law (“Choyles”)

Pressure-Volume-Temperature relationship

This law can be used to determine how changing two variables at a time affects a third variable.

1 1 2 2

1 2

P V P V =

T T

Combined Gas Law Example: A gas occupies 72.0 mL at 25 °C and 198 kPa. Convert these to standard conditions. What is the new volume?

P1 = 198 kPa P2 = 101.325 kPa

V1 = 72.0 mL V2 = ?

T1 = 298 K T2 = 273 K

2

2

198 kPa 72.0 mL 101.325 kPa V =

298 K 273 K129 mL = V

1 1 2 2

1 2

P V P V =

T T

Dalton’s Law of Dalton’s Law of Partial PressurePartial Pressure

Gases in a mixture behave independently of each other.

The total pressure of a gaseous mixture equals the sum of the partial pressures of the individual gases in a mixture.

Partial pressure = individual pressure of a gas in a mixture

PT = p1 + p2 + p3 + …

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

Example #1) A flask contains a mixture of oxygen, argon, and Example #1) A flask contains a mixture of oxygen, argon, and carbon dioxide with partial pressures of 745 torr, carbon dioxide with partial pressures of 745 torr, 0.278 atm, 0.278 atm, and 391 torr respectively. What is the total pressure in the and 391 torr respectively. What is the total pressure in the flask?flask?

PT = Pa + Pb + Pc + …

760 torr.278 atm = 211 torr

1 atm

+ 745 torr

+ 391 torr

1347 torr

In the lab, gases are collected over water (water displacement). As a result, water vapor contributes to the total pressure.

PT = pdry gas + pwater vapor

where pwater vapor varies with temperature

Dalton’s Law of Dalton’s Law of Partial PressurePartial Pressure

T (oC) P (mm Hg) T (oC) P (mm Hg) T (oC) P (mm Hg) T (oC) P (mm Hg)

0 4.6 26 25.2 51 97.2 76 301.4

1 4.9 27 26.7 52 102.1 77 314.1

2 5.3 28 28.4 53 107.2 78 327.3

3 5.7 29 30.0 54 112.5 79 341.0

4 6.1 30 31.8 55 118.0 80 355.1

5 6.5 31 33.7 56 123.8 81 369.7

6 7.0 32 35.7 57 129.8 82 384.9

7 7.5 33 37.7 58 136.1 83 400.6

8 8.1 34 39.9 59 142.6 84 416.8

9 8.6 35 42.2 60 149.4 85 433.6

10 9.2 36 44.6 61 156.4 86 450.9

11 9.8 37 47.1 62 163.8 87 468.7

12 10.5 38 49.7 63 171.4 88 487.1

13 11.2 39 52.4 64 179.3 89 506.1

14 12.0 40 55.3 65 187.5 90 525.8

15 12.8 41 58.3 66 196.1 91 546.1

16 13.6 42 61.5 67 205.0 92 567.0

17 14.5 43 64.8 68 214.2 93 588.6

18 15.5 44 68.3 69 223.7 94 611.0

19 16.5 45 71.9 70 233.7 95 634.0

20 17.5 46 75.7 71 243.9 96 658.0

21 18.7 47 79.6 72 254.6 97 682.0

22 19.8 48 83.7 73 265.7 98 707.3

23 21.1 49 88.0 74 277.2 99 733.2

24 22.4 50 92.5 75 289.1 100 760.0

25 23.8  

EudiometerEudiometer Piece of glassware used Piece of glassware used

to to measure the measure the change in volume of a change in volume of a gasgas. It is similar to a . It is similar to a graduated cylinder. It is graduated cylinder. It is closed at the top end closed at the top end with the bottom end with the bottom end immersed in water or immersed in water or mercury. The liquid traps mercury. The liquid traps a sample of gas in the a sample of gas in the cylinder, and the cylinder, and the graduation allows the graduation allows the volume of the gas to be volume of the gas to be measured. measured.

Example #2) Atmospheric pressure is 101.3kPa, Example #2) Atmospheric pressure is 101.3kPa, and air is a mixture of Nand air is a mixture of N22, O, O22, and Ar as 78.0%, , and Ar as 78.0%,

21.0%, and 1.0%, respectively. Calculate the 21.0%, and 1.0%, respectively. Calculate the partial pressure of Opartial pressure of O22. .

21.3 kPa

Example #3) Hydrogen gas is collected by water displacement at 18°C. Air pressure on that day is 744.0 mm. Calculate the pressure due to the dry hydrogen gas.

728.5 mm Hg