3 Energy Balances Thermodynamics Kinetics英文文献资料

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1、CHAPTER3EnergyBalances:Thermodynamics–KineticsThecrystalstructureandchemicalcompositionofpureandinterstratifiedclayspeciesbeingfamiliar(seeChaps.1and2),itispossiblenowtoinvestigateamoresubtleconsequence:thedistributionofenergyinsidethecrystallatticeanditsin

2、nerandoutersurfaces.Indeed,ifthisisunderstood,thenitbe-comespossibletorelatethecrystallochemicalcharacteristicsofclaymineralstothephysicochemicalconditionsprevailingduringtheirformation.Thisisafascinatingperspectiveforchemists,mineralogistsandgeologistswho

3、,fordifferentbutconvergingreasons,dealwithmineralreactionsinclaymaterials.Particularly,thismakesitpossibletostudytheeffectsformoreorlesslongperiodsoftimeofchemicalinteractionsinhumanenvironments(pollution,cropping,wastestorageetc).3.1ThermodynamicsofEquili

4、brium3.1.1IntroductionThecharacterisationofaclay,orofanyothermineralspecies,requiresthedeterminationofitstridimensionalstructureandchemicalcomposition.Thisamountstoaspacerepresentationofallthechemicalbondsfixingcationsandanionsinacrystallatticewhosesmallest

5、entityisthecrystalunitcell.Eachtypeofbond(positionoftheioninthestructure)ischaracterisedbyapotentialenergy.Eachionvibratingoroscillatingaboutthispositionaddsakineticenergy.Thesumofthepotentialandkineticenergiesformtheenthalpy(H)ofthecrystal.Entropy(S)isapa

6、rameterthatdescribesquantitativelythedegreeofinternaldisorderofasubstance.Vapourhasahigherentropythanwater,whichitselfhasahigherentropythanice.Thisconceptisveryimportantbecauseitpermitsdefinitionofthemajorparametercontrollingchemicalreactions:freeenergy(G):

7、Gcryst=Hcryst−TScryst(3.1)Enthalpyandentropyincreasewiththemassorvolumeofthecrystal;theyareextensivevariables.Theyareexpressedinrelationtothe“molecule”rep-108EnergyBalances:Thermodynamics–KineticsFig.3.1.Respectivedomains)ofthermodynamicsandGkineticstransi

8、torystategy(enerEakineticsGrinitialstate(reactants)∆GthermodynamicsGpfinalstate(products)degreeofreactionprogressresentativeofthecrystal,namelythecrystalunitcell:HinJmol−1andSinJK−1mol−1.Thefirstlawofthermodyn