chapter 9 solutions (1)

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1、Chapter9SolutionsSolutionCompositionSolutions(9.1)*Asolutionisahomogeneousmixture;thatis,asolutionisaone-phasesystemwithmorethanonecomponent.Themolefractionxiofspeciesiisdefinedby(1.6)The(molar)concentration(orvolumeconcentration)ciofspeciesiisdefinedbyThe

2、massconcentrationiofspeciesiinasolutionofvolumeVisdefinedby(9.2)*PhysicalChemistrySolutionCompositionSolutionsThemolarityisthemolarconcentrationofaspeciesforliquidsolutionsinmolesperliter(dm3).ThemolaritymiofspeciesiinasolutionisdefinedbyThesolutemolarity

3、mBis(9.3)*SolutionSolvent(A)Solute(B)(1.4)PhysicalChemistryPartialMolarQuantitiesSolutionsThestarindicatesapropertyofapuresubstanceoracollectionofpuresubstances.(9.4)PartialMolarVolumes0255075100V(ethanol)/cm3100999897967550250V(H2O)/cm3V/cm3Additionof50.0

4、cm3ofwaterto50.0cm3ofethanolat20oCand1atmgivesasolutionof96.5cm3(Fig.9.1,left).PhysicalChemistryPartialMolarQuantitiesSolutions0255075100V(ethanol)/cm3100999897967550250V(H2O)/cm3V/cm3(1)differentintermolecularforces(2)differentpackingofmolecules(different

5、sizesandshapesofthemoleculesbeingmixed)(9.5)ThetotaldifferentialofV(9.6)PhysicalChemistryPartialMolarQuantitiesSolutions(9.6)Thepartialmolarvolume(9.7)*PhysicalChemistrynj:theamountofasubstancejnij:theamountofallothersubstancespresentareconstantPartialMol

6、arQuantitiesSolutionsThepartialmolarvolume(9.7)*(9.8)Equation(9.6)becomesPhysicalChemistryV(a)V(b)xVThepartialmolarvolumeistheslopeofthegraphofthetotalvolumeastheamountofjischanged,P,T,amountofothercomponentsbeingconstantPartialMolarQuantitiesSolutionsThep

7、artialmolarvolume(9.7)*Thepartialmolarvolumeofapuresubstanceisequaltoitsmolarvolume.(9.9)However,thepartialmolarvolumeofcomponentjofasolutionisnotnecessarilyequaltothemolarvolumeofpurej.(9.10)*PhysicalChemistrySolutionvolumeandpartialmolarvolumesSolutionsD

8、ifferentiationof(9.12)atconstantT,P,x1,x2,……,xrgives(9.12)(9.15)(9.13)Equation(9.8)atconstantTandPbecomesAtfixedxi,PhysicalChemistrySolutionvolumeandpartialmolarvolumesSolutionsComparisonoftheexpressions(9.13