AP Chemistry Day 2

Tuesday, August 29th – Wednesday, August 30th, 2017

AP Chemistry Day 2

Do-Now:1.   Turn in your syllabus (back

page only) and lab safety form. Make sure any allergies are clearly written. HW box is by front door.

2.   Take out your planner/calendar (or something else to write your HW down in if you haven’t picked one up yet)

3.   Take out your phone to play a quick Kahoot

CW/HWAssignments1.  Lab Safety WS 8/28 2.  Ch. 1 Notes 8/29 3.  Ch. 1 Review WS 8/29

PLANNER •  Finish WS + Get #1-3 Stamped

•  Study Ch. 1+ 2 à Test next week J

•  Bring class materials

The Exam Big Ideas

1.  Structure of Matter

2.  Bonding and Intermolecular Forces

3.  Chemical Reactions

4.  Kinetics

5.  Thermodynamics

6.  Chemical Equilibrium

Science Practices

1.  Drawing, explaining, & interpreting representations

2.  Using mathematics and logical routines appropriately

3.  Asking and refining scientific questions

4.  Designing and implementing data collection strategies

5.  Analyzing and evaluating data

6.  Making predictions and justifying claims with evidence

7.  Connecting chemistry concepts across the big ideas

The Exam: 3 hours and 15 minutes •  Part I: Multiple Choice (90 minutes) – 50% of score

•  60 Questions, pencil

•  NO calculators

•  Part II: FRQs (105 minutes) – 50% of score •  3 long FRQs, 4 short FRQs •  Any calculator can be used

The exam is designed to have an average score of 50% (AKA yes, it’s

supposed to feel difficult, and that’s okay)

2017 Exam •  Score distribution (for all test-takers):

•  5 – 9.2 %

•  4 – 15.7 %

•  3 – 26.1 %

•  2 – 27%

•  1 – 22%

•  3 students out of 160,000 worldwide earned all 100/100 points possible

•  Students did best on atomic structure, and the least well on equilibrium

Essen5alknowledgestandards•  1.E.1: Physical and chemical processes can

be depicted symbolically; when this is done, the illustration must conserve all atoms of all types

•  2.A.3: Solutions are homogeneous mixtures in which the physical properties are dependent on the concentration of the solute and the strengths of all interactions among the particles of the solutes and solvent.

FLT•  I will be able to:

• Describe and practice the scientific method

• Use mathematical relationships to convert between different units

•  Identify significant figures and use them in mathematical computations

• Describe the different classifications of matter

•  By completing Ch. 1 Notes

Ch.1:ChemicalFounda2ons

Introduction

Chemistry-Introduc5on•  Idea:MaDeriscomposedofatoms•  Canweviewatoms?

–  Individualatomscanbeviewedbyusingascanningtunnelingmicroscope(STM)

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Chemistry-Introduc5on•  Keepinmind:

– Didthescien5stswhodevelopedatomictheoryactuallyseeatoms?

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Chemistry-Introduc5on•  Proper5esofasubstancecanbedeterminedbythewayinwhichatomsareorganizedinthatsubstance

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Chemistry-Introduc5onWhenanelectriccurrentispassedthroughwater,itdecomposestohydrogenandoxygen

•  Bothchemicalelementsexistnaturallyasdiatomic(two-atom)molecules

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Chemistry-Introduc5on•  MaDeriscomposedofvarioustypesofatoms•  ByreorganizingthewaytheatomsareaDachedtoeachother,onesubstancechangestoanother

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TheScien5ficMethod

TheScien5ficMethod•  Framework/procedureforgainingandorganizingknowledge

•  Scien5ficmethodàscien5ficinquiry•  Itstartswithanobserva5onthatgeneratesaques5on

TheScien5ficMethodFirst:Observe•  Qualita5ve(5senses)orquan5ta5ve(measurements)

•  ThisshouldgenerateaQUESTION

TheScien5ficMethodSecond:Generateahypothesis•  Ahypothesisisapossibleexplana5onforanobserva5on

•  O]enwriDeninacondi5onalformat,suchasif____,then_____

TheScien5ficMethodThird:Test!•  Performexperiment(s)•  Recorddataandanalyzetoaccept/rejectyourhypothesis

•  Experimentsproducenewobserva5onsthatusuallyrequiretheprocesstoberepeated/adjusted

TheScien5ficMethod•  Whendoesitbecomeatheory?•  Theory(model):Setoftestedhypothesesthatgivesanoverallexplana5onofanaturalphenomenon(inotherwords,lotsandlotsofexperimentssupportthisidea)– Explana5onofwhynaturebehavesinacertainway– Constantlyrefinedorreplacedasmoreinforma5onbecomesavailable

Pair-Share-Respond1.  Whatisma6ercomposedof?

2.   Iden2fythemainpartsofthescien2ficmethod.

3.   Provideanexampleofaqualita'veobserva2on

4.   Provideanexampleofaquan'ta'veobserva2on

5.   Youno2cethatyourhouseplantisdying.Comeupwithaspecifichypothesisinthe“If___,then____”formtotestwhy. 23

UnitsofMeasurement

UnitsofMeasurement•  Measurementsconsistofanumberandascale(unit)

•  SISystem(interna5onal)isstandardsystem

UnitsofMeasurement•  Table1.2�PrefixesUsedintheSISystem

UnitsofMeasurement•  Table1.3�SomeExamplesofCommonlyUsedUnits

UnitsofMeasurement•  Volume•  Derivedunit(length)

UnitsofMeasurement•  Figure1.6�CommonTypesofLaboratoryEquipmentUsedtoMeasureLiquidVolume

UnitsofMeasurement•  MassvsWeight•  Mass:Measureoftheresistanceofanobjecttoachangeinitsstateofmo5on– Measuredbytheforcenecessarytogiveanobjectacertainaccelera5on

•  Weight:Forceexertedbygravityonanobject– Varieswiththestrengthofthegravita5onalfield

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Uncertainty

UncertaintyinMeasurement•  Differentmeasuringdeviceshavedifferentprecisions

UncertaintyinMeasurement•  Certaindigits

– Numbersthatremainthesameregardlessofwhomeasuresthem

•  Uncertaindigits– Digitsthatmustbees5matedandthereforevary

Measurements:RecordALLcertaindigits+oneuncertaindigit

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UncertaintyinMeasurement•  Readvolumesatthemeniscus– Certaindigits-20.1– Uncertaindigit-20.15

UncertaintyinMeasurement•  Significantfigures:Numbersinwhichthecertaindigitsandthefirstuncertaindigitarerecorded– Uncertaintyinthelastnumberisalwaysassumedtobe±1unlessotherwiseindicated

Pair-Share-Respond•  Inanalyzingasampleofpollutedwater,achemistmeasuredouta25.00-mLwatersamplewithapipet– Atanotherpointintheanalysis,thechemistusedagraduatedcylindertomeasure25mLofasolu5on

– Whatisthedifferencebetweenthemeasurements25.00mLand25mL?

UncertaintyinMeasurement•  Accuracy:Describeshowclosetothe“true”valueameasurementis

•  Precision:Howreproduciblemeasurementsareinreferencetoeachother

UncertaintyinMeasurement•  TypesofErrors•  Randomerror(intermediateerror)

– Measurementhasanequalprobabilityofbeingloworhigh

– Occursines5ma5ngthevalueofthelastdigitofameasurement

Largerandomerrors Smallrandomerrorsandalarge

systema5cerror

Smallrandomerrorsandnosystema5c

error

UncertaintyinMeasurement•  TypesofErrors•  Systema5cerror(determinateerror)

– Occursinthesamedirec5oneach5me– Eitheralwayshighoralwayslow

Largerandomerrors Smallrandomerrorsandalarge

systema5cerror

Smallrandomerrorsandnosystema5c

error

Pair-Share-Respond•  Theglasswareshownbelowiscalledaburet.Theburetisfilledtothezeromark(atthetop)withasolu5on,andthesolu5onistransferredtoabeaker

• Whatvolumeoftransferredsolu5onshouldbereported?

a.  20mL b.  22mLc.  22.0mLd.  22.00mLe.  25mL

UncertaintyinMeasurement

•  Theboilingpointofaliquidwasmeasuredinthelab,withthefollowingresults:

– Theactualboilingpointoftheliquidis28.7°C

Trial Boilingpoint

1 22.0°C±0.12 22.1°C±0.13 21.9°C±0.1

Pair-Share-Respond•  Theresultsofthedetermina5onoftheboilingpointare:a.  accurateandpreciseb.  precisebutinaccuratec.  accuratebutimprecised.  inaccurateandimprecise

– Theactualboilingpointoftheliquidis28.7°C

Trial Boilingpoint

1 22.0°C±0.12 22.1°C±0.13 21.9°C±0.1

Pair-Share-Respond•  _____reflectsthereproducibilityofagiventypeofmeasurementa.  Accuracyb.  Precisionc.  Certaintyd.  Systema5cerrore.  Randomerror

Pair-Share-Respond•  _____istheagreementofapar5cularvaluewiththetruevaluea.  Accuracyb.  Precisionc.  Certaintyd.  Systema5cerrore.  Randomerror

SigFigs

SigFigs•  Rules:1.  Nonzerointegersarealwayssignificant2.  Leadingzeroesarenotsignificant3.  Cap5ve/In-betweenzeroesaresignificant4.  Trailingzeroesaresignificantifadecimalpointis

present

SigFigs•  A]erperformingacalcula5oninthelab,thedisplayonyourcalculatorreads�0.023060070�– Ifthenumberintheansweristohavefivesignificantfigures,whatresultshouldyoureport?a.  0.0230b. 0.00231c.  0.023060d. 0.2367e.  0.02306

Pair-Share-Respond•  Howmanysigfigsin…?1.  1002.  1.0x1023.  1.00x1034.  100.5.  0.00486.  0.004807.  4.80x10-38.  4.800x10-3

SigFigs•  Note:Exactnumbers

–  Determinedbycoun5ngandnotbyusingameasuringdevice

–  Assumedtohaveaninfinitenumberofsignificantfigures

–  Canarisefromdefini5ons–  Example-2in2πr –  Ihave20gloves

•  Thishasinfinitesigfigsbecauseitisanexactnumber,andisnotmeasured.

SigFigs•  Mul5plica5onordivision

– Youranswershouldhavethesamenumberofsigfigsasthenumberisyourleastprecisemeasurement

SigFigs•  Addi5onorsubtrac5on

– Youranswershouldhavethesamenumberofdecimalplacesasyourleastprecisemeasurementused.

Example:– 12.11+18.0+1.013

SigFigs•  Rounding•  RoundoffonlywhenyougetyourFINALRESULT(dimensionalanalysisisyourfriend)

•  Youranswermaybeverydifferentwhenyouroundsequen5ally

•  Yourtextbookspecificallystatesthatitroundsoffeachsteptoshowsigfigs,butthatthismakestheiranswerdifferentàbecarefulwhenlookingatsomeoftheexamples.

SigFigs•  Rounding• Whatifyouwereaskedtoroundtothehundredthsplacefor…– 2.835?– 2.845?

SigFigs•  Rulesforrounding:

– Followwhatyou’velearnedaboutrounding– Ifthelastdigitis5,roundthenumbersothatitwillbeeven

– Ex/– 2.835à2.84– 2.845à2.84

Pair-Share-Respond•  Roundthefollowingtotwodecimalplaces:1.  3.6824172.  21.8600513.  45.46734.  7.5555.  3.665•  Calculateandroundifnecessary:

1.  1.05×10–3÷6.1352.  21–13.8

SigFigs•  Thebeakersbelowhavedifferentprecisions

Pair-Share-Respond•  Youpourthewaterfromthesethreebeakersintoonecontainer– Whatisthevolumeinthiscontainerreportedtothecorrectnumberofsignificantfigures?a.  78.817mLb.  78.82mLc.  78.8mLd.  79mL

DimensionalAnalysis

DimensionalAnalysis•  DimensionalAnalysis(UnitFactorMethod)•  Helpsconvertagivenresultfromonesystemofunitstoanother

DimensionalAnalysis•  Conver5ngfromoneunittoanother•  Theequivalencestatementgoesintotheunitfactor(ex/102cm=1m)

•  Theunityou’restar5ngwithalwaysgoesontheboDom(tocancelout)

•  Theunityouwanttoendupwithgoesontop

DimensionalAnalysis•  Ex/•  Youwanttoorderabicyclewitha25.5-inframe,butthesizesinthecatalogaregivenonlyincen5meters– Whatsizeshouldyouorder?

Example:•  Ex/Howmanycen5metersarein4.50meters?

TryThis:•  Ex/Howmanykilometersarein256cen5meters?

Temperature

Temperature•  K=oC+273•  oC=K–273

•  oC=oF–321.8•  oF=1.8(oC)+32

•  (technically,it�s273.15forKàCorCàK,butwecanuse273)

•  It�snotdegreesKelvin,justKelvin

Temperature•  Withrespecttosignificantfigures

– ForoCàKorKàoC,sincetheconversioninvolvesaddi5onorsubtrac5on,it�sallabouttheprecisionofthegiventemperature• 85oC+273=358K• 85.5oC+273=358.5K• 85.55oC+273=353.55K

– ForoCàoForoFàoC,youwillhavetoconsiderthenumberofsignificantfiguresandtheprecision• 275.6oCbecomes528.1oF• 105.6oFbecomes40.9oC

Trythis:•  Ex/Oneinteres5ngfeatureoftheCelsiusandFahrenheitscalesisthat–40°Cand–40°Frepresentthesametemperature– Verifythatthisistrue(oF=1.8(oC)+32)

Density

Density•  DensityàPropertyofmaDerthatisusedasaniden5fica5ontagforsubstances

•  Densityofaliquidcanbedeterminedeasilybyweighinganaccuratelyknownvolumeofliquid

Density•  Ex/Achemist,tryingtoiden5fyanunknownliquid,findsthat25.00cm3ofthesubstancehasamassof19.625gat20°C

•  Whichcompoundismostthemostlikelyiden5fyoftheunknown?

Density•  Table1.5-Densi5esofVariousCommonSubstances*at20°C

Pair-Share-Respond•  Ex/A25gcylinderofiron(d=7.87g/mL)anda1.0grampelletofcopper(d=8.96g/mL)areplacedin500mLofwater(d=0.9982g/mL)– Predictwhethereachwillfloatorsinkinwater

a.  Ironwillfloat,andcopperwillsinkb.  Ironwillsink,andcopperwillfloatc.  Ironandcopperwillsinkd.  Ironandcopperwillfloate.  Moreinforma5onisneeded

Classifica5onofMaDer

Classifica5onofMaDer•  MaDer=Anythingthatoccupiesspaceandhasmass•  Hasmanylevelsoforganiza5onandiscomplex•  Existsinthreestates

– Solid– Liquid– Gas

Classifica5onofMaDer•  Solids

– Rigid– Fixedvolumeandshape– Slightlycompressible

Classifica5onofMaDer•  Liquids

– Definitevolume– Nospecificshape

• Assumestheshapeofitscontainer

– Slightlycompressible

Classifica5onofMaDer•  Gases•  Nofixedvolumeorshape

– Takesontheshapeandvolumeofitscontainer

•  Highlycompressible– Rela5velyeasytodecreasethevolumeofagas

Separa5ngMixturesIntoPureSubstances

Separa5ngMixtures•  Mixtures-havevariablecomposi5on•  Classifica5on

– Homogeneousmixture:Hasvisiblyindis5nguishablepartsandiso]encalledasolu5on

– Heterogeneousmixture:Hasvisiblydis5nguishableparts

•  Canbeseparatedintopuresubstances,whichhaveconstantcomposi5ons,byphysicalmethods

Separa5ngMixtures•  PhysicalChange•  Changeintheformofasubstance

– Nochangeinthechemicalcomposi5onofthesubstance

•  Example– Boilingorfreezingofwater

•  Usedtoseparateamixtureintopurecompounds– Willnotbreakcompoundsintoelements

Separa5ngMixtures

MethodsforSepara5ngComponentsinaMixture

Dis2lla2on Filtra2on

Chromatography

Separa5ngMixtures•  Dis5lla5on•  Dependsonthedifferencesinthevola5lityofthecomponents

•  Worksbestwhenoneofthesubstancesisvola5le,andtheotherisnot,asthemostvola5lecomponentvaporizesatthelowesttemperature

•  Ex/dis5lla5onofseawater

Classifica5onofMaDer•  Filtra5on•  Usedwhenamixtureconsistsofasolidandaliquid•  Mixtureispouredontoamesh,suchasfilterpaper,whichpassestheliquidandleavesthesolidbehind

Classifica5onofMaDer•  Chromatography•  Generalnameappliedtoaseriesofmethodsthatuseasystemwithtwostates(phases)ofmaDer– Mobilephase-Liquidorgas– Sta5onaryphase-Solid

•  Separa5onoccursbecausethecomponentsofthemixturehavedifferentaffini5esforthetwophases– Theymovethroughthesystematdifferentrates

Classifica5onofMaDer•  Chromatography

– Componentwithahighaffinityforthemobilephasewillquicklygothroughthechromatographicsystemascomparedtoonewithahighaffinityforthesolidphase

•  Paperchromatography:Usesastripofporouspaperforthesta5onaryphase

Classifica5onofMaDer•  PureSubstances•  Eithercompoundsorfreeelements

– Compound:Substancewithaconstantcomposi5onthatcanbebrokendownintoitselementsviachemicalprocesses

•  Givensubstancebecomesanewsubstanceorsubstanceswithdifferentproper5esanddifferentcomposi5on

– Element:Substancethatcannotbebrokendownintosimplersubstancesbyphysicalorchemicalmeans

Classifica5onofMaDer

Pair-Share-Respond•  Asolu5onisalsoa:

a.  heterogeneousmixtureb.  homogeneousmixturec.  compoundd.  dis5lledmixturee.  puremixture

Pair-Share-Respond•  Whichofthefollowingstatementsisfalse?

a.  Solu5onsarealwayshomogeneousmixturesb.  Atomsthatmakeupasolidaremostlyopenspacec.  Elementscanexistasatomsormoleculesd.  Compoundscanexistaselementsormolecules

Assignment1.  ZumdahlCh.1(10e)WS

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