第四章 有机过渡金属络合物的合成ppt课件.ppt

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1、PhysicalChemistrySecondlawofthermodynamics:Concepts3.TheSecondLaw:theconceptsThischapterwillexplaintheoriginofthespontaneityofphysicalandchemicalchange.Twosimpleprocessesareexamined.Itshowsthataproperty,theentropycanbedefined,measured,andusedtodiscussspontaneouschangesquantitatively.Thisc

2、hapteralsointroducesamajorsubsidiarythermodynamicproperty,theGibbsenergy.3.TheSecondLaw:theconceptsTheintroductionoftheGibbsenergyenablesthespontaneityofaprocesstobeexpressedsolelyintermsofthepropertiesofasystem(insteadofhavingtoconsiderentropychangesinthesystemanditssurroundings).TheGibb

3、senergyalsoenablesustopredictthemaximumofexpansionworkthataprocesscando.3.TheSecondLaw:theconceptsThedirectionofspontaneouschange3.1Thedispersalofenergy3.2Entropy3.3Entropychangesaccompanyingspecificprocesses3.4TheThirdLawofthermodynamics3.5ReachingverylowtemperaturesConcentratingonthesys

4、tem3.6TheHelmholtzandGibbsenergies3.7StandardmolarGibbsenergiesThedirectionofspontaneouschangeSomethingshappennaturally.Agasexpandstofilltheavailablevolume,ahotbodycoolstothetemperatureofitssurroundings,andachemicalreactionrunsinonedirectionratherthananother.Butsomethingsdon't.Wecanconfin

5、eagastoasmallervolume,wecancoolanobjectwitharefrigerator,andwecanforcesomereactionstogoinreverse.However,noneoftheseprocesseshappensspontaneously.Thedirectionofspontaneouschange3.1ThedispersalofenergySketchforthedistributionofenergy3.1ThedispersalofenergyThespontaneouschangesarealwaysacco

6、mpaniedbyadispersalofenergyintoamoredisorderedform.SketchforthedistributionofenergyThedirectionofspontaneouschange3.1Thedispersalofenergy(a)Aballrestingonawarmsurface;theatomsareundergoingthermalmotion;SketchforthedistributionofenergyThedirectionofspontaneouschange(b)Fortheballtoflyupward

7、s,someoftherandomvibrationalmotionwouldhavetochangeintocoordinate,directedmotion.3.1ThedispersalofenergyThedirectionofspontaneouschangeInthetermofentropyTheentropyofanisolatedsystemincreasesinthecourseofaspontaneouschange:whereStotisthetotalentropyofthesystemanditss