Page 1
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.
Page 2
(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
Page 3
Ch.1:ChemicalFoundations
Page 4
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
Page 6
Chemistry-Introduction• Idea:Matteriscomposedofatoms• Canweviewatoms?
– Individualatomscanbeviewedbyusingascanningtunnelingmicroscope(STM)
55
Page 7
Chemistry-Introduction• Keepinmind:
– Didthescientistswhodevelopedatomictheoryactuallyseeatoms?
56
Page 8
Chemistry-Introduction• Propertiesofasubstancecanbedeterminedbythewayinwhichatomsareorganizedinthatsubstance
57
Page 9
Chemistry-IntroductionWhenanelectriccurrentispassedthroughwater,itdecomposestohydrogenandoxygen
• Bothchemicalelementsexistnaturallyasdiatomic(two-atom)molecules
58
Page 10
Chemistry-Introduction• Matteriscomposedofvarioustypesofatoms• Byreorganizingthewaytheatomsareattachedtoeachother,onesubstancechangestoanother
59
Page 11
ScientificInquiryProcess
Page 12
ScientificInquiryProcess• Framework/procedureforgainingandorganizingknowledge
• Scientificmethodàscientificinquiry• Itstartswithanobservationthatgeneratesaquestion
Page 14
TheScientificMethodFirst:Observe• Qualitative(5senses)orquantitative(measurements)
• ThisshouldgenerateaQUESTION
Page 15
TheScientificMethodSecond:Generateahypothesis• Ahypothesisisapossibleexplanationforanobservation
• Oftenwritteninaconditionalformat,suchasif____,then_____
• Beabletomakeclaims
Page 16
TheScientificMethodThird:Test!• Performexperiment(s)• Recorddataandanalyzetoaccept/rejectyourhypothesis
• Experimentsproducenewobservationsthatusuallyrequiretheprocesstoberepeated/adjusted
Page 17
TheScientificMethod• Whendoesitbecomeatheory?• Theory(model):Setoftestedhypothesesthatgivesanoverallexplanationofanaturalphenomenon(inotherwords,lotsandlotsofexperimentssupportthisidea)– Explanationofwhynaturebehavesinacertainway– Constantlyrefinedorreplacedasmoreinformationbecomesavailable
Page 18
Pair-Share-Respond1. Whatismattercomposedof?2. Identifythemainpartsofthescientific
method.3. Provideanexampleofaqualitative
observation4. Provideanexampleofaquantitative
observation5. Younoticethatyourhouseplantisdying.
Comeupwithaspecifichypothesisinthe“If___,then____”formtotestwhy. 67
Page 19
UnitsofMeasurement
Page 20
UnitsofMeasurement• Measurementsconsistofanumberandascale(unit)
• SISystem(international)isstandardsystem
Page 21
UnitsofMeasurement• Table1.2–PrefixesUsedintheSISystem
Page 22
UnitsofMeasurement• Table1.3–SomeExamplesofCommonlyUsedUnits
Page 23
UnitsofMeasurement• Volume• Derivedunit(length)
Page 24
UnitsofMeasurement• Figure1.6–CommonTypesofLaboratoryEquipmentUsedtoMeasureLiquidVolume
Page 25
UnitsofMeasurement• MassvsWeight• Mass:Measureoftheresistanceofanobjecttoachangeinitsstateofmotion– Measuredbytheforcenecessarytogiveanobjectacertainacceleration
• Weight:Forceexertedbygravityonanobject– Varieswiththestrengthofthegravitationalfield
Page 28
UncertaintyinMeasurement• Differentmeasuringdeviceshavedifferentprecisions
Page 29
UncertaintyinMeasurement• Certaindigits
– Numbersthatremainthesameregardlessofwhomeasuresthem
• Uncertaindigits– Digitsthatmustbeestimatedandthereforevary
Measurements:RecordALLcertaindigits+oneuncertaindigit
Page 32
UncertaintyinMeasurement• Readvolumesatthemeniscus– Certaindigits-20.1– Uncertaindigit-20.15
Page 33
UncertaintyinMeasurement• Significantfigures:Numbersinwhichthecertaindigitsandthefirstuncertaindigitarerecorded– Uncertaintyinthelastnumberisalwaysassumedtobe±1unlessotherwiseindicated
Page 34
Pair-Share-Respond• Inanalyzingasampleofpollutedwater,achemistmeasuredouta25.00-mLwatersamplewithapipet– Atanotherpointintheanalysis,thechemistusedagraduatedcylindertomeasure25mLofasolution
– Whatisthedifferencebetweenthemeasurements25.00mLand25mL?
Page 35
UncertaintyinMeasurement• Accuracy:Describeshowclosetothe“true”valueameasurementis
• Precision:Howreproduciblemeasurementsareinreferencetoeachother
Page 36
UncertaintyinMeasurement• TypesofErrors• Randomerror(intermediateerror)
– Measurementhasanequalprobabilityofbeingloworhigh
– Occursinestimatingthevalueofthelastdigitofameasurement
Largerandomerrors Smallrandomerrorsandalarge
systematicerror
Smallrandomerrorsandnosystematic
error
Page 37
UncertaintyinMeasurement• TypesofErrors• Systematicerror(determinateerror)
– Occursinthesamedirectioneachtime– Eitheralwayshighoralwayslow
Largerandomerrors Smallrandomerrorsandalarge
systematicerror
Smallrandomerrorsandnosystematic
error
Page 38
Pair-Share-Respond• Theglasswareshownbelowiscalledaburet.Theburetisfilledtothezeromark(atthetop)withasolution,andthesolutionistransferredtoabeaker
• Whatvolumeoftransferredsolutionshouldbereported?
a. 20mL b. 22mLc. 22.0mLd. 22.00mLe. 25mL
Page 39
UncertaintyinMeasurement
• Theboilingpointofaliquidwasmeasuredinthelab,withthefollowingresults:
– Theactualboilingpointoftheliquidis28.7°C
Trial Boilingpoint
1 22.0°C±0.12 22.1°C±0.13 21.9°C±0.1
Page 40
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
Page 41
UncertaintyinMeasurement• _____reflectsthereproducibilityofagiventypeofmeasurementa. Accuracyb. Precisionc. Certaintyd. Systematicerrore. Randomerror
Page 42
UncertaintyinMeasurement• _____istheagreementofaparticularvaluewiththetruevaluea. Accuracyb. Precisionc. Certaintyd. Systematicerrore. Randomerror
Page 44
SigFigs• Rules:1. Nonzerointegersarealwayssignificant2. Leadingzeroesarenotsignificant3. Captive/In-betweenzeroesaresignificant4. Trailingzeroesaresignificantifadecimalpointis
present
Page 45
SigFigs• Afterperformingacalculationinthelab,thedisplayonyourcalculatorreads“0.023060070”– Ifthenumberintheansweristohavefivesignificantfigures,whatresultshouldyoureport?a. 0.0230b. 0.00231c. 0.023060d. 0.2367e. 0.02306
Page 46
Pair-Share-Respond• Howmanysigfigsin…?1. 1002. 1.0x1023. 1.00x1034. 100.5. 0.00486. 0.004807. 4.80x10-38. 4.800x10-3
Page 47
SigFigs• Note:Exactnumbers
– Determinedbycountingandnotbyusingameasuringdevice
– Assumedtohaveaninfinitenumberofsignificantfigures
– Canarisefromdefinitions– Example-2in2πr – Ihave20gloves
• Thishasinfinitesigfigsbecauseitisanexactnumber,andisnotmeasured.
Page 48
SigFigs• Multiplicationordivision
– Youranswershouldhavethesamenumberofsigfigsasthenumberisyourleastprecisemeasurement
Page 49
SigFigs• Additionorsubtraction
– Youranswershouldhavethesamenumberofdecimalplacesasyourleastprecisemeasurementused.
Example:– 12.11+18.0+1.013
Page 50
SigFigs• Rounding• Unlessyourproblemisseparatedintosteps,roundoffonlywhenyougetyourFINALRESULT
• Youranswermaybeverydifferentwhenyouroundsequentially
• Yourtextbookspecificallystatesthatitroundsoffeachsteptoshowsigfigs,butthatthismakestheiranswerdifferentàbecarefulwhenlookingatsomeoftheexamples.
Page 51
SigFigs• Rounding• Whatifyouwereaskedtoroundtothehundredthsplacefor…– 2.835?– 2.845?
Page 52
SigFigs• Rulesforrounding:
– Followwhatyou’velearnedaboutrounding– Ifthelastdigitis5,roundthenumbersothatitwillbeeven
– Ex/– 2.835à2.84– 2.845à2.84
Page 53
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
Page 54
SigFigs• Thebeakersbelowhavedifferentprecisions
Page 55
SigFigs• Youpourthewaterfromthesethreebeakersintoonecontainer– Whatisthevolumeinthiscontainerreportedtothecorrectnumberofsignificantfigures?a. 78.817mLb. 78.82mLc. 78.8mLd. 79mL
Page 56
DimensionalAnalysis
Page 57
DimensionalAnalysis• DimensionalAnalysis(UnitFactorMethod)• Helpsconvertagivenresultfromonesystemofunitstoanother
Page 58
DimensionalAnalysis• Convertingfromoneunittoanother• Theequivalencestatementgoesintotheunitfactor(ex/102cm=1m)
• Theunityou’restartingwithalwaysgoesonthebottom(tocancelout)
• Theunityouwanttoendupwithgoesontop
Page 59
DimensionalAnalysis• Ex/• Youwanttoorderabicyclewitha25.5-inframe,butthesizesinthecatalogaregivenonlyincentimeters– Whatsizeshouldyouorder?
Page 60
DimensionalAnalysis• Ex/Howmanycentimetersarein4.50meters?
Page 61
TryThis:• Ex/Howmanykilometersarein256centimeters?
Page 63
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
Page 64
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
Page 65
Temperature• Ex/OneinterestingfeatureoftheCelsiusandFahrenheitscalesisthat–40°Cand–40°Frepresentthesametemperature– Verifythatthisistrue(oF=1.8(oC)+32)
Page 67
Density• Density• Propertyofmatterthatisusedasanidentificationtagforsubstances
• Densityofaliquidcanbedeterminedeasilybyweighinganaccuratelyknownvolumeofliquid
Page 68
Density• Ex/Achemist,tryingtoidentifyanunknownliquid,findsthat25.00cm3ofthesubstancehasamassof19.625gat20°C
• Whichcompoundismostthemostlikelyidentifyoftheunknown?
Page 69
Density• Table1.5-DensitiesofVariousCommonSubstances*at20°C
Page 70
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
Page 71
ClassificationofMatter
Page 72
ClassificationofMatter• Matter=Anythingthatoccupiesspaceandhasmass• Hasmanylevelsoforganizationandiscomplex• Existsinthreemainstates
– Solid– Liquid– Gas
Page 73
ClassificationofMatter• Solids
– Rigid– Fixedvolumeandshape– Slightlycompressible
Page 74
ClassificationofMatter• Liquids
– Definitevolume– Nospecificshape
• Assumestheshapeofitscontainer
– Slightlycompressible
Page 75
ClassificationofMatter• Gases• Nofixedvolumeorshape
– Takesontheshapeandvolumeofitscontainer
• Highlycompressible– Relativelyeasytodecreasethevolumeofagas
Page 76
SeparatingMixturesIntoPureSubstances
Page 77
SeparatingMixtures• Mixtures-havevariablecomposition• Classification
– Homogeneousmixture:Hasvisiblyindistinguishablepartsandisoftencalledasolution
– Heterogeneousmixture:Hasvisiblydistinguishableparts
• Canbeseparatedintopuresubstances,whichhaveconstantcompositions,byphysicalmethods
Page 78
SeparatingMixtures• PhysicalChange• Changeintheformofasubstance
– Nochangeinthechemicalcompositionofthesubstance
• Example– Boilingorfreezingofwater
• Usedtoseparateamixtureintopurecompounds– Willnotbreakcompoundsintoelements
Page 79
SeparatingMixtures
MethodsforSeparatingComponentsinaMixture
Distillation Filtration
Chromatography
Page 80
SeparatingMixtures• Distillation• Dependsonthedifferencesinthevolatilityofthecomponents
• Worksbestwhenoneofthesubstancesisvolatile,andtheotherisnot,asthemostvolatilecomponentvaporizesatthelowesttemperature
• Ex/distillationofseawater
Page 81
ClassificationofMatter• Filtration• Usedwhenamixtureconsistsofasolidandaliquid• Mixtureispouredontoamesh,suchasfilterpaper,whichpassestheliquidandleavesthesolidbehind
Page 82
ClassificationofMatter• Chromatography• Generalnameappliedtoaseriesofmethodsthatuseasystemwithtwostates(phases)ofmatter– Mobilephase-Liquidorgas– Stationaryphase-Solid
• Separationoccursbecausethecomponentsofthemixturehavedifferentaffinitiesforthetwophases– Theymovethroughthesystematdifferentrates
Page 83
ClassificationofMatter• Chromatography
– Componentwithahighaffinityforthemobilephasewillquicklygothroughthechromatographicsystemascomparedtoonewithahighaffinityforthesolidphase
• Paperchromatography:Usesastripofporouspaperforthestationaryphase
Page 84
ClassificationofMatter• PureSubstances• Eithercompoundsorfreeelements
– Compound:Substancewithaconstantcompositionthatcanbebrokendownintoitselementsviachemicalprocesses
• Givensubstancebecomesanewsubstanceorsubstanceswithdifferentpropertiesanddifferentcomposition
– Element:Substancethatcannotbebrokendownintosimplersubstancesbyphysicalorchemicalmeans
Page 86
ClassificationofMatter
Page 87
ClassificationofMatter• Asolutionisalsoa:
a. heterogeneousmixtureb. homogeneousmixturec. compoundd. distilledmixturee. puremixture
Page 88
ClassificationofMatter• Whichofthefollowingstatementsisfalse?
a. Solutionsarealwayshomogeneousmixturesb. Atomsthatmakeupasolidaremostlyopenspacec. Elementscanexistasatomsormoleculesd. Compoundscanexistaselementsormolecules