結(jié)構(gòu)物化廈大chapter12

1Chapter12ponentPhaseEquilibriumPhysicalChemistryponentPhase2QuestionandAnswering

PhysicalChemistryAStudent’sQuestion我昨天晚上看了第9章的38題，想到了一個(gè)問題，在2種組分的理想混合溶液中，一種組分所占整個(gè)體系的摩爾分?jǐn)?shù)與它的蒸汽所占整個(gè)體系氣體的摩爾分?jǐn)?shù)和它的液態(tài)部分所占整個(gè)體系液態(tài)部分的摩爾分?jǐn)?shù)之間有什么關(guān)系？也就是與和三者有什么關(guān)系？是不是？但仔細(xì)想又不對(duì)！

Question:3QuestionandAnswering

PhysicalChemistryAStudent’sQuestionRaoult’sLaw:Answers.Dalton’sLaw:ABCase(1)Case(2)Case(3)4ColligativeProperties

Colligativepropertiesstemfromthereductionofthechemicalpotentialoftheliquidsolventasaresultofthepresenceofsolute.ColligativePropertiesVapor-pressureloweringFreezing-pointdepressionBoiling-pointelevationOsmoticpressureThesoluteisnotvolatileThesolutedoesnotdissolveinthesolidsolventPhysicalChemistryponentPhase5ColligativeProperties

Vapor-pressureloweringPA/torrx(sucrose)0-400.1Fig.12.1nonvolatilesolute(12.1)nonvolatilesolute(12.2)(Nocontributiontothevapor)Ifthesolutionisverydilute,ideallydilutesolution,nonvolatilesolute(12.3)ideallydilutesolutionPhysicalChemistryponentPhase6ColligativeProperties

Freezing-pointdepression(12.13)ideallydil.soln.,pureAfreezesoutmolarfreezing-point-depressionconstant

ATFig.12.2A(s)A(l)A(sln)Freezing-pointdepression(12.15)*(12.16)PhysicalChemistryponentPhase7ColligativeProperties

Boiling-pointelevationideallydil.soln.,nonvol.solutemolarboiling-point-elevationconstant(12.18)*(12.19)

ATA(l)A(s)A(v)Boiling-pointelevationPhysicalChemistryponentPhase8ColligativeProperties

Thevaporpressureofapureliquidrepresentsabalancebetweentheincreaseddisorderarisingfromvaporizationandthedecreaseddisorderofthesurroundings.

Whensoluteispresent,thedisorderofthecondensedphaseisrelativelyhigherthanthatofthepureliquid,andthereisadecreasedtendencytoacquirethedisordercharacteristicofthevapor.PhysicalChemistryponentPhase9ColligativeProperties

Equilib.atTforvaporandliquidphasesofthesolventrearrangesto(AssumingTindependent)WhenxB=0,theboilingpointisandPhysicalChemistryponentPhase10ColligativeProperties

SupposethattheamountofsolutepresentissosmallthatthenPhysicalChemistryponentPhase11ColligativeProperties

sinceitalsofollowsthat(P344)ForverydilutesolutionPhysicalChemistryponentPhase12ColligativeProperties

Osmoticpressure(12.20)(12.26)EqualatequilibriumPureASolutionofB+ASemipermeablemembrane(A)ideallydil.soln.(12.27)*van’tHoff’slaw,validinthelimitofinfinitedilutionPhysicalChemistryponentPhase13ColligativeProperties

OsmoticpressureTheosmoticpressureinanonideallydilutenonelectrolyteponentsolution(12.28)(8.4)Inthelimitofinfinitesolutionvan’tHofflawPhysicalChemistryponentPhase14f=2－φ＋2＝4－φ，φ＝1， f＝3φ＝2， f＝2φ＝3， f＝1φ＝4， f＝0 ponentphasediagramsIfonephase,thenthreefreedoms:TPxInsteadofplottingcompletephasediagrams(threedimensional),usuallyconsideronlyportionofthephasediagramatatime.PhysicalChemistryponentPhase15ponentphasediagramsKeeponeconstant,getrelationsfortwovariablesKeepTconstant,getP-x(verycommonlyused)KeepPconstant,getT-x(commonlyused)Keepxconstant,getT-P(notverycommonlyused)PhysicalChemistryponentPhase16l(A+B)C6H5CH3(A)C6H6(B)yB0.00.20.40.60.81.00.80.60.20.40.00.00.20.40.60.81.0v(A+B)T=79.7

℃yG,B=0.60HFxBl(A+B)Il(A+B)v(A+B)P/102kPatielineADEisoplethlineH,IendpointIdealsolutionatfixedTPhysicalChemistryponentPhase17l(A+B)010.80.60.20.40.00.00.20.40.60.81.0v(A+B)T=79.7

℃HFxBl(A+B)Il(A+B)v(A+B)P/102kPaADEponentphasediagrams(12.40)(12.39)LeverrulePhysicalChemistryponentPhase180.01.0l(A+B)C6H5CH3(A)C6H6(B)xByB12010060800.00.00.20.40.60.81.0t/℃v(A+B)P=101325PaliquidSQRLNTemperaturevscompositionliquid-vaporphasediagram(C6H5CH3(A)-C6H6(B))l+vIdealsolutionatfixedPvaporBoiling-pointcurvePSuccessiveboilingsandcondensationsofaliquidoriginallyofcompositiona1leadtoacondensatethatispureBa1FractionaldistillationPhysicalChemistryponentPhase19ponentphasediagramsNonidealSolutionAlow-boilingazeotropeAhigh-boilingazeotropeminimum-boilingazeotropemaximum-boilingazeotropelVapor

l+vVapor

Liquid

l+vl+vl+vAzeotropes

PhysicalChemistryponentPhase20ponentphasediagramsAmaximuminthephasediagrammayoccurwhenthefavorableinteractionsbetweenAandBmoleculesreducethevaporpressureofthemixturebelowtheidealvaluePhasediagramshowingaminimumPhasediagramshowingamaximumThemixture:formanazeotropeWhentheazeotropiccompositionhasbeenreached,distillationcannotseparatethetwoliquidsbecausethecondensatehasthesamecompositionastheazeotropicliquid.PhysicalChemistryponentPhase21ponentphasediagramsExamplesofazeotropeformation:Hydrochloricacid/waterat80%bymassofwaterandboilsunchangedat108.6oC.Ethanol/waterat4%bymassofwaterandboilsunchangedat78.0oC.Ahigh-boilingazeotrope.Alow-boilingazeotrope.PhysicalChemistryponentPhase22ponentphasediagramsLiquid-liquidequilibriumTwopartiallymiscibleliquids0.00.20.40.60.81.0l(A+B)H2O(A)C6H5NH2(B)xBt/℃1601204080P=const.T