ap chemistry day 2
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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)
11
Chemistry-Introduc5on• Keepinmind:
– Didthescien5stswhodevelopedatomictheoryactuallyseeatoms?
12
Chemistry-Introduc5on• Proper5esofasubstancecanbedeterminedbythewayinwhichatomsareorganizedinthatsubstance
13
Chemistry-Introduc5onWhenanelectriccurrentispassedthroughwater,itdecomposestohydrogenandoxygen
• Bothchemicalelementsexistnaturallyasdiatomic(two-atom)molecules
14
Chemistry-Introduc5on• MaDeriscomposedofvarioustypesofatoms• ByreorganizingthewaytheatomsareaDachedtoeachother,onesubstancechangestoanother
15
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
31
Uncertainty
UncertaintyinMeasurement• Differentmeasuringdeviceshavedifferentprecisions
UncertaintyinMeasurement• Certaindigits
– Numbersthatremainthesameregardlessofwhomeasuresthem
• Uncertaindigits– Digitsthatmustbees5matedandthereforevary
Measurements:RecordALLcertaindigits+oneuncertaindigit
35
36
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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