Solutions--University-of-Massachusetts-Lowell解决的方案麻州大学的洛厄尔课件.ppt

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1、SolutionsAhomogeneousmixtureoftwoormoresubstances.TheSolutionProcessWewillfocusonsolidorliquidsolutesdissolvedinaliquidsolvent.Sinceallparticlesareincontactwitheachother,thesolute-soluteandsolvent-solventforcesofattractionaredisrupted,andnew,solute-solventforcesofattractionarecreated.TheSol

2、utionProcessThedisruptionofsolute-soluteandsolvent-solventforcesofattractionrequiresenergy,andisendothermic.Theinteractionofsolventandsoluteusuallyreleasesenergy.Thesumoftheenergyofallthreestepsiscalledtheenthalpyofsolution,ΔHosoln.Notethatsolutionsmayformwhetherthenetprocessisendothermicor

3、exothermic.TheSolutionProcessTheSolutionProcessInadditiontotheenthalpyofsolution,wemustalsoconsidertheentropyofmixing.Entropyisameasureofrandomnessordisorder.Anincreaseinentropymakesaprocessmorelikelytooccur.Sincemixingpuresubstancesincreasesentropy,thisfactormakesprocessesthatareslightlyen

4、dothermicfavorable.EntropyofMixingTheSolutionProcessThegeneralruleonsolutionformationis:Likedissolveslike.Polarandioniccompoundsdissolveinpolarsolvents.Non-polarcompoundsdissolveinnon-polarsolvents.LikeDissolvesLikeVitaminAconsistsalmostentirelyofcarbonandhydrogen,andisnon-polar.Asaresult,v

5、itaminAisfat-soluble,andcanbestoredinthebody.LikeDissolvesLikeVitaminCcontainspolarC-OandO-Hbonds.Itiswatersoluble,andmustbeconsumedoften,asitisexcretedeasily.O-HbondsC-ObondLikeDissolvesLikeIonicCompoundsLikeDissolvesLikeTheSolutionProcessDisrupt-ionofsoluteDisrupt-ionofsolventSolute/Solv

6、entinteract-ionIonicAqueousSolutionsWhenanioniccompoundisdissolvedinwater,theenergyrequiredtoseparatetheionsofthesoluteisequalto–(latticeenergy),or-ΔHlattice.Theenergyreleasedasthegaseousionsdissolveinwateriscalledthehydrationenergy,ΔHhydration.ThenetenergychangeisΔHsoln.HeatofHydrationFact

7、orsAffectingSolubilityMolecularStructurePressure(forgaseoussolutes)TemperaturePressureEffectsGasesdissolvedinaliquidsoluteobeyHenry’sLaw:C=kPwhereCistheconcentration,kisaconstantspecifictosoluteandsolvent,andPisthepressureofthegasabovethesolutionPressure