Essential knowledge standards - Ms. Flemingflemingapchem.weebly.com/.../ap_chem_ch_1_ppt.pdf · •...

Essentialknowledgestandards•  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.

(Intro)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:ChemicalFoundations

TakingNotesinClass•  Take notes on bigger ideas, not

every little detail •  DO copy down all problems/

calculations •  After class, go to website to review

powerpoint and add useful details to notes

Introduction

Chemistry-Introduction•  Idea:Matteriscomposedofatoms•  Canweviewatoms?

–  Individualatomscanbeviewedbyusingascanningtunnelingmicroscope(STM)

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Chemistry-Introduction•  Keepinmind:

– Didthescientistswhodevelopedatomictheoryactuallyseeatoms?

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Chemistry-Introduction•  Propertiesofasubstancecanbedeterminedbythewayinwhichatomsareorganizedinthatsubstance

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Chemistry-IntroductionWhenanelectriccurrentispassedthroughwater,itdecomposestohydrogenandoxygen

•  Bothchemicalelementsexistnaturallyasdiatomic(two-atom)molecules

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Chemistry-Introduction•  Matteriscomposedofvarioustypesofatoms•  Byreorganizingthewaytheatomsareattachedtoeachother,onesubstancechangestoanother

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ScientificInquiryProcess

ScientificInquiryProcess•  Framework/procedureforgainingandorganizingknowledge

•  Scientificmethodàscientificinquiry•  Itstartswithanobservationthatgeneratesaquestion

TheScientificMethodFirst:Observe•  Qualitative(5senses)orquantitative(measurements)

•  ThisshouldgenerateaQUESTION

TheScientificMethodSecond:Generateahypothesis•  Ahypothesisisapossibleexplanationforanobservation

•  Oftenwritteninaconditionalformat,suchasif____,then_____

•  Beabletomakeclaims

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

•  Experimentsproducenewobservationsthatusuallyrequiretheprocesstoberepeated/adjusted

TheScientificMethod•  Whendoesitbecomeatheory?•  Theory(model):Setoftestedhypothesesthatgivesanoverallexplanationofanaturalphenomenon(inotherwords,lotsandlotsofexperimentssupportthisidea)– Explanationofwhynaturebehavesinacertainway– Constantlyrefinedorreplacedasmoreinformationbecomesavailable

Pair-Share-Respond1.  Whatismattercomposedof?2.   Identifythemainpartsofthescientific

method.3.   Provideanexampleofaqualitative

observation4.   Provideanexampleofaquantitative

observation5.   Younoticethatyourhouseplantisdying.

Comeupwithaspecifichypothesisinthe“If___,then____”formtotestwhy. 67

UnitsofMeasurement

UnitsofMeasurement•  Measurementsconsistofanumberandascale(unit)

•  SISystem(international)isstandardsystem

UnitsofMeasurement•  Table1.2–PrefixesUsedintheSISystem

UnitsofMeasurement•  Table1.3–SomeExamplesofCommonlyUsedUnits

UnitsofMeasurement•  Volume•  Derivedunit(length)

UnitsofMeasurement•  Figure1.6–CommonTypesofLaboratoryEquipmentUsedtoMeasureLiquidVolume

UnitsofMeasurement•  MassvsWeight•  Mass:Measureoftheresistanceofanobjecttoachangeinitsstateofmotion– Measuredbytheforcenecessarytogiveanobjectacertainacceleration

•  Weight:Forceexertedbygravityonanobject– Varieswiththestrengthofthegravitationalfield

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Uncertainty

UncertaintyinMeasurement•  Differentmeasuringdeviceshavedifferentprecisions

UncertaintyinMeasurement•  Certaindigits

– Numbersthatremainthesameregardlessofwhomeasuresthem

•  Uncertaindigits– Digitsthatmustbeestimatedandthereforevary

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,thechemistusedagraduatedcylindertomeasure25mLofasolution

– Whatisthedifferencebetweenthemeasurements25.00mLand25mL?

UncertaintyinMeasurement•  Accuracy:Describeshowclosetothe“true”valueameasurementis

•  Precision:Howreproduciblemeasurementsareinreferencetoeachother

UncertaintyinMeasurement•  TypesofErrors•  Randomerror(intermediateerror)

– Measurementhasanequalprobabilityofbeingloworhigh

– Occursinestimatingthevalueofthelastdigitofameasurement

Largerandomerrors Smallrandomerrorsandalarge

systematicerror

Smallrandomerrorsandnosystematic

error

UncertaintyinMeasurement•  TypesofErrors•  Systematicerror(determinateerror)

– Occursinthesamedirectioneachtime– Eitheralwayshighoralwayslow

Largerandomerrors Smallrandomerrorsandalarge

systematicerror

Smallrandomerrorsandnosystematic

error

Pair-Share-Respond•  Theglasswareshownbelowiscalledaburet.Theburetisfilledtothezeromark(atthetop)withasolution,andthesolutionistransferredtoabeaker

• Whatvolumeoftransferredsolutionshouldbereported?

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•  Theresultsofthedeterminationoftheboilingpointare: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

UncertaintyinMeasurement•  _____reflectsthereproducibilityofagiventypeofmeasurementa.  Accuracyb.  Precisionc.  Certaintyd.  Systematicerrore.  Randomerror

UncertaintyinMeasurement•  _____istheagreementofaparticularvaluewiththetruevaluea.  Accuracyb.  Precisionc.  Certaintyd.  Systematicerrore.  Randomerror

SigFigs

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

present

SigFigs•  Afterperformingacalculationinthelab,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

–  Determinedbycountingandnotbyusingameasuringdevice

–  Assumedtohaveaninfinitenumberofsignificantfigures

–  Canarisefromdefinitions–  Example-2in2πr –  Ihave20gloves

•  Thishasinfinitesigfigsbecauseitisanexactnumber,andisnotmeasured.

SigFigs•  Multiplicationordivision

– Youranswershouldhavethesamenumberofsigfigsasthenumberisyourleastprecisemeasurement

SigFigs•  Additionorsubtraction

– Youranswershouldhavethesamenumberofdecimalplacesasyourleastprecisemeasurementused.

Example:– 12.11+18.0+1.013

SigFigs•  Rounding•  Unlessyourproblemisseparatedintosteps,roundoffonlywhenyougetyourFINALRESULT

•  Youranswermaybeverydifferentwhenyouroundsequentially

•  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

SigFigs•  Youpourthewaterfromthesethreebeakersintoonecontainer– Whatisthevolumeinthiscontainerreportedtothecorrectnumberofsignificantfigures?a.  78.817mLb.  78.82mLc.  78.8mLd.  79mL

DimensionalAnalysis

DimensionalAnalysis•  DimensionalAnalysis(UnitFactorMethod)•  Helpsconvertagivenresultfromonesystemofunitstoanother

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

•  Theunityou’restartingwithalwaysgoesonthebottom(tocancelout)

•  Theunityouwanttoendupwithgoesontop

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

DimensionalAnalysis•  Ex/Howmanycentimetersarein4.50meters?

TryThis:•  Ex/Howmanykilometersarein256centimeters?

Temperature

Temperature(don’tmemorize)•  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,sincetheconversioninvolvesadditionorsubtraction,it’sallabouttheprecisionofthegiventemperature• 85oC+273=358K• 85.5oC+273=358.5K• 85.55oC+273=353.55K

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

Temperature•  Ex/OneinterestingfeatureoftheCelsiusandFahrenheitscalesisthat–40°Cand–40°Frepresentthesametemperature– Verifythatthisistrue(oF=1.8(oC)+32)

Density

Density•  Density•  Propertyofmatterthatisusedasanidentificationtagforsubstances

•  Densityofaliquidcanbedeterminedeasilybyweighinganaccuratelyknownvolumeofliquid

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

•  Whichcompoundismostthemostlikelyidentifyoftheunknown?

Density•  Table1.5-DensitiesofVariousCommonSubstances*at20°C

Density•  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.  Moreinformationisneeded

ClassificationofMatter

ClassificationofMatter•  Matter=Anythingthatoccupiesspaceandhasmass•  Hasmanylevelsoforganizationandiscomplex•  Existsinthreemainstates

– Solid– Liquid– Gas

ClassificationofMatter•  Solids

– Rigid– Fixedvolumeandshape– Slightlycompressible

ClassificationofMatter•  Liquids

– Definitevolume– Nospecificshape

• Assumestheshapeofitscontainer

– Slightlycompressible

ClassificationofMatter•  Gases•  Nofixedvolumeorshape

– Takesontheshapeandvolumeofitscontainer

•  Highlycompressible– Relativelyeasytodecreasethevolumeofagas

SeparatingMixturesIntoPureSubstances

SeparatingMixtures•  Mixtures-havevariablecomposition•  Classification

– Homogeneousmixture:Hasvisiblyindistinguishablepartsandisoftencalledasolution

– Heterogeneousmixture:Hasvisiblydistinguishableparts

•  Canbeseparatedintopuresubstances,whichhaveconstantcompositions,byphysicalmethods

SeparatingMixtures•  PhysicalChange•  Changeintheformofasubstance

– Nochangeinthechemicalcompositionofthesubstance

•  Example– Boilingorfreezingofwater

•  Usedtoseparateamixtureintopurecompounds– Willnotbreakcompoundsintoelements

SeparatingMixtures

MethodsforSeparatingComponentsinaMixture

Distillation Filtration

Chromatography

SeparatingMixtures•  Distillation•  Dependsonthedifferencesinthevolatilityofthecomponents

•  Worksbestwhenoneofthesubstancesisvolatile,andtheotherisnot,asthemostvolatilecomponentvaporizesatthelowesttemperature

•  Ex/distillationofseawater

ClassificationofMatter•  Filtration•  Usedwhenamixtureconsistsofasolidandaliquid•  Mixtureispouredontoamesh,suchasfilterpaper,whichpassestheliquidandleavesthesolidbehind

ClassificationofMatter•  Chromatography•  Generalnameappliedtoaseriesofmethodsthatuseasystemwithtwostates(phases)ofmatter– Mobilephase-Liquidorgas– Stationaryphase-Solid

•  Separationoccursbecausethecomponentsofthemixturehavedifferentaffinitiesforthetwophases– Theymovethroughthesystematdifferentrates

ClassificationofMatter•  Chromatography

– Componentwithahighaffinityforthemobilephasewillquicklygothroughthechromatographicsystemascomparedtoonewithahighaffinityforthesolidphase

•  Paperchromatography:Usesastripofporouspaperforthestationaryphase

ClassificationofMatter•  PureSubstances•  Eithercompoundsorfreeelements

– Compound:Substancewithaconstantcompositionthatcanbebrokendownintoitselementsviachemicalprocesses

•  Givensubstancebecomesanewsubstanceorsubstanceswithdifferentpropertiesanddifferentcomposition

– Element:Substancethatcannotbebrokendownintosimplersubstancesbyphysicalorchemicalmeans

ClassificationofMatter

ClassificationofMatter•  Asolutionisalsoa:

a.  heterogeneousmixtureb.  homogeneousmixturec.  compoundd.  distilledmixturee.  puremixture

ClassificationofMatter•  Whichofthefollowingstatementsisfalse?

a.  Solutionsarealwayshomogeneousmixturesb.  Atomsthatmakeupasolidaremostlyopenspacec.  Elementscanexistasatomsormoleculesd.  Compoundscanexistaselementsormolecules