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1、2.1.3ProcessandPathway(1)Theprocessofstatechangeisnamedaspathway,suchasisothermalprocess,isobaricprocess,isochoricprocess(2)In these regards,the process that a system experiencesfromtheinitialstatetothefinalstateisnamedasthepathstate.(3)Fromstate1tostate2,thepathwayisdifferent,butthechangevaluesofpa
2、rametersinstatefunctioncanbethesame.(4)Whenthestateisfixed,thenumericalvaluesinthestatefunctioncanbeprovided.(5)Asfarastheinitialandfinalstatesaredetermined,thechangedvaluesofparametersinthestatefunctionpresentonlynumber.(6)Forisobaricprocesses,Pisequaltozero.Forisochoricprocesses,V is equal to zero
3、,For isothermal process,T isequaltozero.298K,101.3kPa298K,506.5kPa375K,101.3kPa375K,506.5kPaIsothermalprocessPath(II)IsochoricprocessPath(I)(I)Isobaricprocess(II)actualprocessTheactualprocessandthedesignedprocessaredifferentIsothermalprocess2.1.4phase:Thephysicalandchemicalpropertiesinthefixedsystem
4、 are same,in which the homogeneous part isdefinedasaphase.Thereisaclearinterfacebetweenthephases.SinglephasesystemAccordingtothephasenumbersinthesystem:Multiphasesystem(twophase,threephase)Water(l)SugarwaterSugarwatersugar homogeneoussystemmultiphasesystem 2.1.5stoichiometricequationandreactionprogr
5、ess(1)Thestoichiometricequation:chemicalreactionequations.(2)Thecorrectchemicalformula(3)Whetherreactantorreactionproduct,itshouldindicateitsspecificstate:g,l,s,aq.(4)Theconservationofatomandcharge.Thestoichiometriccoefficients:thecoefficientsatthefrontoftheformulahavetobesignedplusorminus.Thecoeffi
6、cientofreactantsisnegative,otherwise,otherspositive.aA(g)+bB(g)=gG(g)+dD(g)A=-aB=-bG=gD=dReactiveprogress():inordertoelucidatethatthe chemical reaction is going on,Donder,theBelgianchemist,proposedaconcept.Itsunitisexpressedinmole.aA+bB=gG+dDExample1:when3molesofnitrogenreactwithtenmolesofhydrogenth
7、roughthereactiontowerandthengothroughmanycycles,finally,2molesofammoniaisgenerated.valuecouldbecalculatedusingfollowingtworeactionequations:(a)N2+3H2=2NH3(b)1/2N2+3/2H2=NH3Thephysicalmeaningof=1mole:thereactionachievesaunitreactionaccordingtothecoefficientproportionofthestoichiometriccoefficientforr
8、eactionformula:(1)Thevaluemustbecorrespondingtothestoichiometricreactionformula.(2)Forthesamechemicalreactionformula,thecalculatedvalueexpressedbyreactiveorproductivesubstanceisthesame.nB/mol 3.0 10.0 0 0 nB/mol 2.0 7.0 2.0nB/mol 1.5 5.5 3.0 t=t0:t=t1:t=t2:2.0 7.0 2.0 (mol)3.0 10.0 0 (mol)t=0t=t1(1)Thevaluemustbecorrespondingtothestoichiometricreactionformula.(2)Forthesamechemicalreactionformula,thecalculatedvalueexpressedbyreactiveorproductivesubstanceisthesame.