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Analyticalchemistry2024/5/511/46IntroductiontoAnalyticalChemistry22024/5/52/4632024/5/5

Analyticalchemistryinvolvesseparating,identifying,anddeterminingtherelativeamountsofthecomponentsmakingupasampleofmatter.

分析化學(xué)包含樣品分離、定性以及確定組成成份相對(duì)含量三方面內(nèi)容。

Qualitativeanalysisrevealsthechemicalidentityoftheanalytes.

定性分析是確定被分析物(待測(cè)物)化學(xué)組成。3/4642024/5/5

Quantitativeanalysistellsustherelativeamountsofoneormoreoftheseanalytesinnumericalterms.

定量分析是確定一個(gè)或各種不一樣形式被分析物相對(duì)含量。

Qualitativeinformationisrequiredbeforeaquantitativeanalysiscanbeundertaken.

在進(jìn)行定量分析之前需要先進(jìn)行定性分析。Aseparationstepisusuallyanecessarypartofbothqualitativeandqualitativeanalysis.

通常情況下，樣品預(yù)先分離是進(jìn)行定性和定量分析之前必不可少步驟。4/46TheroleofanalyticalchemistryinthescienceAnalyticalchemistry,ortheartofrecognizingdifferentsubstancesanddeterminedtheirconstituents,

takesaprominentpositionamongtheapplicationsofscience,sincethequestionswhichitenablesustoanswerarisewheneverchemicalprocessesareemployedforscientificortechnicalpurpose.分析化學(xué)是一門確定不一樣物質(zhì)組成及其含量學(xué)科，在科學(xué)應(yīng)用中處于主導(dǎo)地位。這是因?yàn)榉治龌瘜W(xué)能夠幫助我們處理全部利用化工能處理科學(xué)和技術(shù)所產(chǎn)生問(wèn)題。52024/5/55/46Itssupremeimportancehascausedittobeassiduouslycultivatedfromaveryearlyperiodinthehistoryofchemistry,anditsrecordscomprisealargepartofthequantitativeworkwhichisspreadoverthewholedomainofscience.分析化學(xué)主要性使其在化學(xué)歷史最早期就得到了全方面發(fā)展，同時(shí)分析化學(xué)統(tǒng)計(jì)包含了大部分定量分析工作，并在整個(gè)科學(xué)領(lǐng)域得到廣泛傳輸。62024/5/56/46Quantitativeanalyticalmeasurementalsoplayavitalroleinmanyresearchareasinchemistry,biochemistry,biology,geology,andtheothersciences.定量分析測(cè)量也在化學(xué)、生物化學(xué)、生物學(xué)、地理學(xué)以及其它科學(xué)許多研究領(lǐng)域飾演者主要角色。72024/5/57/46Forexample,chemists

unravelthemechanismsofchemicalreactionsthrough

reaction-ratestudies,therateatwhichreactantsareconsumedorproductsformedinachemicalreactioncanbecalculatedfromquantitativemeasurementsmadeatequaltimeintervals.比如，化學(xué)家經(jīng)過(guò)研究反應(yīng)速率來(lái)說(shuō)明化學(xué)反應(yīng)機(jī)理。而化學(xué)反應(yīng)中反應(yīng)物消耗速率或產(chǎn)物生成速率能夠經(jīng)過(guò)在相同時(shí)間間隔下進(jìn)行定量測(cè)計(jì)算得到。82024/5/58/46Quantitativeanalysisforpotassium,calcium,andsodiumionsinthebodyfluidsofanimalspermit

physiologiststostudytheroletheseionsplayinnerve-signalconductionandmusclecontractionandrelaxation.生理學(xué)家經(jīng)過(guò)對(duì)動(dòng)物體液內(nèi)鉀離子、鈣離子和鈉離子定量分析，來(lái)研究這些離子在神經(jīng)信號(hào)傳導(dǎo)和肌肉收縮和松弛中作用。92024/5/59/46Materialsscientistsrelyheavilyuponquantitativeanalysisofcrystallinegermaniumandsiliconintheirstudiesofthebehaviorofsemiconductordevices.材料學(xué)家主要依賴對(duì)晶體鍺和硅定量分析來(lái)研究他們作為半導(dǎo)體元件性能。Impuritiesinthesedevicesareintheconcentrationsrange1*10-6to1*10-10percent.這些元件中雜質(zhì)含量在百分之1*10-6

到1*10-10范圍內(nèi)。

102024/5/510/46Archaeologistsidentifythesourceofvolcanicglassesbymeasuringtheconcentrationsofminorelementsinsamplestakenfromvariouslocations.考古學(xué)家經(jīng)過(guò)測(cè)量從不一樣位置采集樣品中微量元素濃度來(lái)確定火山玻璃巖起源。Thisknowledgeinturnmakesitpossibletotraceprehistorictraderoutesfortoolsandweaponsfashionedfromobsidian.以這類推，這種方法也有望用于史前流行黑曜石工具和武器交易路線追蹤研究。112024/5/511/46AclassificationofquantitativemethodsofanalysisWecomputetheresultsofatypicalquantitativeanalysisfromtwoproductiveamountsofthecomponentsmakingupasampleofmatter.經(jīng)典定量分析結(jié)果是經(jīng)過(guò)計(jì)算組成樣品兩種大量成份含量得到。Qualitativeanalysisrevealsthechemicalmeasurements.定性分析是指化學(xué)測(cè)量。122024/5/512/46Oneistheweightorvolumeofsampletobeanalyzed.第一步是分析樣品重量或體積。Thesecondisthemeasurementofsomequantitythatisproportionaltotheamountofanalyteinthatsample.第二步是測(cè)量與樣品中被分析物相當(dāng)物質(zhì)量。Thissecondsstepnormallycompletestheanalysis.第二步通常是完成份析步驟。132024/5/513/46Chemistsclassifyanalyticalmethodsaccordingtothenatureofthisfinalmeasurement.化學(xué)家依據(jù)最終一步測(cè)量性質(zhì)對(duì)分析方法進(jìn)行分類。Inagravimetricmethod,themassoftheanalyteorofsomecompoundschemicallyrelatedtoitisdetermined.

重量分析法是用來(lái)確定被分析物或其它一些化學(xué)相關(guān)物質(zhì)質(zhì)量。142024/5/514/46Inavolumetricmethod,thevolumeofasolutioncontainingsufficientreagenttoreactcompletelywiththeanalyzerismeasured.容量法是指用含有過(guò)量試劑溶液與被分析物完全反應(yīng)，并測(cè)量反應(yīng)溶液體積方法。Electro-analyticalmethodsinvolvethemeasurementofsuchelectricalpropertiesaspotential,current,resistance,andquantityofelectricity.電化學(xué)分析法是測(cè)量電化學(xué)性質(zhì)方法，如測(cè)量電壓、電流、電阻及電量等。152024/5/515/46Spectroscopicmethodsarebaseduponmeasurementsoftheinteractionbetweenelectromagneticradiationandanalyteatomsormoleculesorupontheproductionofsuchradiationbyanalytes.光譜分析法是基于測(cè)量被分析物原子或分子與電磁輻射之間相互作用，或測(cè)量被分析物產(chǎn)生輻射方法。Finally,agroupofmiscellaneousmethodsshouldbementioned.最終，還應(yīng)介紹一組不一樣種類分析方法。162024/5/516/46Theseincludethemeasurementofsuchpropertiesasmass-to-chargeratio(massspectrometry),rateofradioactivedecay,heatofreaction,rateofreaction,thermalconductivity,opticalactivity,andrefractiveindex.這些分析方法測(cè)量被分析物一些其它性質(zhì)，包含荷質(zhì)比（質(zhì)譜），放射性衰變速率，反應(yīng)熱、反應(yīng)速率、導(dǎo)熱性、光學(xué)活性（旋光度）以及折射率。172024/5/517/46StepinatypicalquantitativeanalysisSelectingamethodSelectingwhichmethodtousetosolveananalyticalproblemisavitalfirststepinanyquantitativeanalysis.在任何定量分析中選擇分析方法是處理問(wèn)題至關(guān)主要第一步。Thechoiceissometimesdifficult,animportantconsiderationinselectionistheaccuracyrequired.有時(shí)極難選擇到適當(dāng)分析方法，其中一個(gè)至關(guān)主要考慮原因就是分析對(duì)準(zhǔn)確度要求。182024/5/518/46Unfortunately,highreliabilitynearlyalwaysrequiredalargeinvestmentoftime.不過(guò)，要取得高可信度普通需要花費(fèi)大量時(shí)間進(jìn)行分析。Thechosenmethodismostoftenacompromisebetweenaccuracyandeconomics.分析方法選擇往往是綜合考慮了準(zhǔn)確度和經(jīng)濟(jì)性兩方面原因。

192024/5/519/46SamplingToproducemeaningfulinformation,ananalysismustbeperformedonasamplewhosecompositionfaithfullyrepresentsthatofthebulkofmaterialfromwhichthesamplewastaken.為了取得有價(jià)值信息，分析所使用樣品必須能夠如實(shí)地代表大部分被分析物組成。Wherethebulkislargeandinhomogeneous,greateffortisrequiredtogetarepresentativesample.當(dāng)待測(cè)物質(zhì)是體積龐大而且組成不均勻樣品時(shí)，想要取得含有代表性樣品并不輕易。202024/5/520/46Consider,forexample,arailroadcarcontaining25tonsofsilverore.比如，試想有一輛裝有15噸銀礦石有軌電車。Buyerandsellermustagreeonthevalueoftheshipmentbasedprimarilyitssilvercontent.買家和賣家對(duì)這批貨物價(jià)值達(dá)成共識(shí)，主要是依據(jù)貨物中銀含量。Theoreisinherentlyheterogeneous,consistingofproductiveamountsofthecomponentsmakingupasampleofmatter.礦石是內(nèi)部均勻，由大量組分組成樣品。

212024/5/521/46PreparingalaboratorysampleAftersampling,solidmaterialsfrequentlyaregroundtodecreaseparticlesize,mixedtoensurehomogently,andstoredforvariouslengthsoftimebeforetheanalysisbegins.取樣后，固體材料通常需要研磨成更小顆粒，并混合均勻，在分析之前需要進(jìn)過(guò)不一樣時(shí)間貯藏。Duringeachofthesesteps,absorptionordesorptionofwatermayoccur,dependinguponthehumidityoftheenvironment.在這些步驟中，可能會(huì)發(fā)生樣品吸水和脫水，這主要取決于環(huán)境濕度。

222024/5/522/46Becauseanylossorgainofwaterchangesthechemicalcompositionofasolid,itisagoodideatocarefullydrysamplesatthestartofananalysis.因?yàn)槿魏嗡秩笔Щ蛉〉枚紩?huì)引發(fā)固體樣品化學(xué)組成改變，所以，在對(duì)樣品分析之前最好先進(jìn)行嚴(yán)格干燥處理。Alternatively,themoisturecontentofthesamplecanbedeterminedattimeoftheanalysisinaseparateanalyticalprocedure.另一個(gè)方法，樣品中水分含量能夠在進(jìn)行分析同時(shí)，經(jīng)過(guò)單獨(dú)分析步驟進(jìn)行測(cè)定。232024/5/523/46DefiningreplicatesamplesMostchemicalanalysisareperformedonreplicatesampleswhoseweightorvolumeshavebeendeterminedbycarefulmeasurementwithananalyticalbalanceorwithaprecisevolumetricdevice.大部分化學(xué)分析都是在隨機(jī)抽樣樣品上進(jìn)行，這些樣品重量和體積已經(jīng)經(jīng)過(guò)分析天平或精密體積測(cè)量設(shè)備測(cè)量給出。Obtainingreplicatedataonsamplesimprovesthequalityoftheresultsandprovidesameasureoftheirreliability.樣品隨機(jī)抽樣數(shù)據(jù)取得提升了分析結(jié)果質(zhì)量，并能夠測(cè)驗(yàn)其分析可信度。

242024/5/524/46PreparesolutionofthesampleMostanalysisareperformedonsolutionofthesample.大多數(shù)分析都是針對(duì)溶液樣品進(jìn)行。Ideally,thesolventshoulddissolvetheentiresamplerapidly.最理想情況是樣品能夠在溶劑中快速完全溶解。Theconditionsofdissolutionshouldbesufficientmildsothatlossoftheanalytecannotoccur.應(yīng)盡可能防止待測(cè)物質(zhì)分解，以降低由此造成損失。252024/5/525/46Unfortunately,manymaterialsthatmustbeanalyzedareinsolubleincommonsolvents.不過(guò)，許多需要分析待測(cè)物質(zhì)在常規(guī)溶劑中極難溶解。Examplesincludesilicateminerals,high-molecule-weightpolymers,andspecimensofanimaltissue.這些物質(zhì)包含硅礦石，高聚物以及動(dòng)物組織標(biāo)本。Conversionoftheanalyteinsuchmaterialstobeasolubleformcanbeadifficultandtime-consumingtask.將上述物質(zhì)轉(zhuǎn)變成可溶物形式進(jìn)行分析，是一項(xiàng)極其困難又耗時(shí)工作。262024/5/526/46CalibrationanmeasurementQualitativeanalysisrevealsthechemicalmanylumpsthatvaryinsizeaswellasinsilvercontent.定性分析是分析許多不一樣尺寸及銀含量化學(xué)塊狀物。Theanalysistohavesignificance,thissmallsamplemusthaveacompositionthatisrepresentativeofthe25tonsoreintheshipment.這種小樣品必須能夠代表這批25噸銀礦石貨物組成，這么定性分析才有意義。272024/5/527/46Thetaskistoisolate1gofmaterialthataccuratelyreflectstheaveragecompositionofthenearly23000000gbulksample.取樣工作就是從待分析物中取出1g樣品，并使其能夠充分代表快要23000000g樣品平均組成。Obtainingsucharepresentativesampleisadifficultundertakingthatrequiresacareful,systematicmanipulationoftheentireshipment.要想取得這么含有代表性樣品相當(dāng)不輕易，它需要對(duì)整個(gè)樣品進(jìn)行仔細(xì)，系統(tǒng)處理。282024/5/528/46AcidsandbasesKeytheory:Bronsted-Lowrytheoryofacidsandbases:Acid-basereactionsareonesinwhichprotonsaregivenandtaken.Acidsareprotondonors,basesareprotonacceptors.292024/5/5HF+H2OH3O++F－

H2O+NH3NH4++OH－AcidbaseConjugateConjugateacidbasetobeabletogiveprotons,andacidmusthaveahydrogenatomwhichcanbelost.tobeabase,asubstancemusthavealonepairwhichcanbecomeasigmapairasitacceptsaproton.29/46ConjugatepairsEveryacidhaswhatiscalledaconjugatebase.Thisistheparticleleftwhentheacidhasgivenawayitsproton.Inthesameway,everybasehasaconjugateacid,whichistheparticlemadewhenprotonhasarrived.SotheconjugatebaseofHClisCl-

andtheconjugateacidofammoniaisNH4+.

Familiarconjugatepairs:302024/5/5-AcHAc

--2442HPOPOH--3424POHPO+34NHNH30/46AmpholytesThewaterinthefirstreactionaboveisactingasabase,oneofitslonepairsacceptsaprotons.Inthesecondreactionthewaterisbeinganacid,givingoneofitsprotonstoammonia.Substanceslikewater,withhydrogensthatcanbelostandlonepairsthatcanbeprotoned,arecalledampholytes.Theycanbeeitheracidsorbasesdependingonwhattheyreactwith.312024/5/5HF+H2OH3O++F－

H2O+NH3NH4++OH－31/46ExerciseWhicharetheconjugatepairsinthebelow?322024/5/5

NH3、OH—、Na+、NH2—、NH4+、Cl—、H+

。Isthereanyampholyte?

NH3NH2—&NH4+NH3&NH332/46IndicatorsIndicatorsaresubstanceswhichchangecolourasthepHchanges.Anindicatorisaweakacidwhoseconjugatebaseisadifferentcolour.

HIn?H3O++In-colourAcolourBInacidtherewillbealotofH3O+andsotheequilibriumwilllietotheleft.ThecolourseenwillbecolourA.Inalkalineconditions,alltheH3O+ionswillbeuesdupandtheequilibriumwillmovetotheright.ThecolourseenwillbecolourB.332024/5/5↑↑33/46IndicatorsWhenthereareequalamountsofthetwocolours,[HIn]willequal[In-]andthecolourwillbeamixtureofAandB.ThishappenswhenpH=pKHInasshownbelow.1

[HIn]=[In-],sopH=pKHInThesuddenchangeincolourseeninatitrationiscalledtheend-point.Somepeoplearecolourblind,butmostpeoplecandetectachangeincolourwhentheratioofAtoBis1:10or10:1.ThismeansmostindicatorshaveausefulpHchangerangeofabout2pHunits.342024/5/5=[H+]KHIn[HIn][In-]34/46EquivalencepointTheequivalencepointofthetitration,whenamountsofacidandbaseexactlybalance,andtheendpointwillbeveryclosetoeachotherifthecorrectindicatorhasbeenchosen.352024/5/535/46IndicatorstructureIndicatorstructurearequitecomplicatedmoleculeswhoseelectronicstructurechangesastheyareprotonatedordeprotonated.Thischangeinelectronicstructureresultsinachangeinelectronicenergylevelsandsoachangeincolour.362024/5/5H+

OH-red3.1orange4.0yellow4.4pKa=3.436/46372024/5/5IndicatorPKInUsefulpHrangeColourchangeMethylorange3.73.1-4.4redtoyellowBromophenolblue4.03.0-4.6yellowtoblueMethylred5.14.2-6.3redtoyellowBromothymolblue7.06.0-7.6yellowtobluePhenolphthalein9.38.0-9.6colourlesstored37/46382024/5/53.14.44.04.26.35.08.09.69.0MethylorangeMOMethylredMRPhenolphthalein

PP38/46BuffersolutionsBuffersolutionsresistchangesinpHonadditionofacidoralkali.BuffersolutionstendtoresistchangesinpHwhensmallamountsofacidorbaseareaddedandtheirpHisnotaffectedbydilution.392024/5/539/46BuffersolutionsAcidbuffersaremadeofasolutionofaweakacidanditsconjugatebase,e.g.asolutionofethanoicacidandsodiumethanoate.Basicbuffersaremadeofasolutionofaweakbaseanditsconjugateacid,e.g.asolutionofammoniaandammoniumchloride.402024/5/540/46Howbufferswork?Wehaveseenthatabuffercontainsparticleswhichcanreactwitheitheranyacidoranybasewhichisadded.412024/5/5CH3COOH+H2OCH3COO-+H3O+Lotsofspareacidmoleculesbecauseethanoicacidisaweakacid.Lotsofspareconjugatebasebecausesodiumethanoatehasbeenaddedtotheacidsolution.41/46AdditionofabaseAnybasethatisaddedreactswiththehydroxoniumions,H3O+,andusesthe