课件上半学期eng sgwhk

Heatcapacity(热容)TheC(T)

δ δ

Dimension:{J.K-TT0T Isochoricmolarheatca 等容摩尔热容 (T)defCV(T)1δV

n nVolarheatcapacity(等压摩尔热容p (T) Cp(T)1δQpp

1Hp

nT EmpiricexpressionofEmpiricexpressionofmolarheatcapacityIsobaricprocess，finitevariationofT2 dT T2−Qp 1

Cp,misnCp,m(T)dT isfunctionof1 1Cp，m＝a＋bT＋cT2＋dT Cp，m＝a′＋b′T＋c′Ta，b，c，c′，dareconstantforgivensubstances,andcanbefoundin Atp，theheatcapacityof2 tiesUwith]

=

=

]

=

-p]p

[U]=

[]-

=(C-C)]p- =-(C-C)

-[

T T tiesHwith]

=

=

=C+V

[H = []+

=V-(C-C) p p =

+(Cp-

T T

Theapplicationofthe1st energy)issolelyfunctionoftemperatureThosegasesthatobeystrictlythefollowingtworulesarecalledperfectgases

Joule1°pV=nRT(Puresubstance) pVniRTi2°U=U

orU

andcomosition5-5th2.7Joule-Thomsoneffect焦耳-汤姆逊效应Theapplicationofthe1stlawinthrottlingflowprocessofarealgas6Frompreviousclass,wehavetheformulaheatcapacityC-Frompreviousclass,wehavetheformulaheatcapacity

Cp-CV={V-T}Thekeypointisto

U

HV V 7From T UU T U T

T

U

TVT

Joule

8FromHp T T H

H T Hp p T

JTCp ( (——

H J-J-H(IsothermalJoule-Thomsoncoefficient,Atkin’s9Joule(AiexpandstoNotsensitive、not1、Theheatcapacityofwaterinthecalorimetervesselismuch hanthatofthegas；2、ItdoesexistJoule-Thomsonexperiment(焦耳 实验绝热 多孔开 p2p2Throttlingflowprocess(节流过程p1Joule-Thomsoneffect(1852),theT,Vhavebeenchangedafterthethrottlingflow

ofetlingBecauseallchangestothegasoccuradiabatically:Q=0.Thegasontheleftiscompressedisothermallyandtheworkdone:WL=-pi(0-Vi)=piViTheworkdoneinWR=-pf(Vf-0)=-ThetotalworkThethermodynamicbasisofJoule-ThomsonW=WL+WR=piViThethermodynamicbasisofJoule-ThomsonThethermodynamicsofthethrottlingflowThethermodynamicJoule-SinceQ=0,thenU=W+Q=W.thechangeofUofthegasasitmovesfromonesideThethermodynamicJoule-Uf-Ui=W=piVi-pfVfUf+pfVf=Ui+piViHf=Theexpansionoccurswithoutchangeofenthalpyanisenthalpicprocess(等H1 isenthalpicprocess(等焓过程TheT，phavebeenbothchanged,whiletheHremainsconstant.ThisindicatesthatthechangeofHwithTH1 isenthalpicprocess(等焓过程p.ItisobviousthattheHofarealgasisfunctionofT，p，andisnotonlyafunctionofT.3Joule-Thomsoncoefficient焦-汤系数

T

T

standsforthechangeratiooftemperaturewithpressureatconstantenthalpyinathrottlingflowprocessSinceSincep＜0(expansion),thetemperatureoffluidthrottlingflowwillrise(T＞0)whenJ-Tdrop(T＜0)J-invariable(T=0)J-(4)(4)Determinationofisenthalps(等焓线的测定得低压气体的一系列T2与(T1，p1)1(p2a,T2a)1p2b,T2b)1与(T1，p1)2相对应得THighestinversiontemperature最高转换温度(T,pTHighestinversiontemperature最高转换温度(T,p 1致冷区inversioncurve转换曲线致温区p >Coolingzone致冷 >J- <Heatingzone致温 <J-TheJoule-Thomsoneffect:forrealThesignoftheJoule-Gasesthatshowaheatingeffect(J-T<0)atoneTshowacoolingeffect(J-T>0)whentheTisbelowtheirupperinversiontemperature,TI.AgastypicallyhastwoThesignoftheJoule-The‘Linderefrigerator’makesuseofJoule-Thomsonexpansiontoliquefygases.(Industrialprocessofliquefyinggas)(5)ThermodynamicsofJoule-ThomsoneffectHighestinversionTm/气Tm/H TV Itcanbe

T

JTheJ-TcanbethencalcudataofCp.

Cp Cp qua From

Hp TpT H

T H H HT

p

pC C

J

H Fromthe2ndlaw

H

TV

p T

J

TV C

FromFromH=U+pV,wecanobtainHpVp UV(pV)TJ

UUVVp (pV)T TCp Cp IfwehavethevalueofU,wecanthen

Besides，fromU=U(V,T)andH=H(p,T),weobtainUVTVTU

UV

J T U CV (pV)JCpHpJCpHp TpT HTHHpJT

U H

J JT.Cp

sinceCV0, J=also,sinceCP0,soJ-T=TpThatis,theperfectgashasnotJoule-Thomsoncoefficient,TpTheJoule-ThomsoneffectsofgascanbediscussedTheJoule-Thomsoneffectsofgascanbediscussedusingequationofstateofreagas.Forexampl, satisfiesthevanderWaalsequation,wehave 2a(Vm–b)2–TheJ- C RTVm–

bTl=——(1–——b Inversion（

—+—2a—+1)–—a—=HU(因为Qp

QpQVn(RT QVQpn(RT所以|QV|ClassDiscussion1.Zn和稀硫酸作用，（1）在敞口瓶，（2）在ClassDiscussion1.Zn和稀硫酸作用，（1）在敞口瓶，（2）在 Zn(s)H2SO4ZnSO4H2(g)此时H=Qp，但Qp0HDiscussionDiscussion3EstimatewhetherQ，W，UandHarezeroornotinthelistedprocesses？Ifnot,pleasejudgewhethertheyarepositiveornegative？QW1.理想气体恒温可逆膨2理想气体节流膨3.理想气体绝热、反抗恒外压4.1mol实际气体5.在绝热容器中,1molH2(g)和1molCl2(g)生成2molHCl(g均为理想气体),fHm[HCl(g)]=-92.31kJ.mol-12.82.8Applicationofthe1stlawofinchemicalreactions(Thermochemistry,热化学IEquationofchemical.Chemicalreactions化学反应）：分子内部原子结合方式及运动形态发生改变的过程(102KJ.mol-1)。分子集方式发生改变的过程(10KJ.mol-1)，分子的种类和数Nuclearreaction（核反应）：原子核 aA+0=B 0=AA+BB+GG+ formulaofBStoichiometricnumber化学计量数）of“–”reactant;“+”productIITheextentofreaction化学反应进度t=

aA+bB=gG+nA°nB°nG°t= Fromtheaboveequation,wenA– nB–nB°nG– nH–———=———=———=— nB–

B nB=

(B=A,B,G,Forclosed

dnB=

SincenB°is d=dnB/ nn

NH 2

H H

10nNH

NH

N2N

H H

20 1 3Thesignificances° doesnotdependonindividualsubstanceinvolvedinthereaction.Thechangeofeachsubstancecanbeevaluatedby describestheentirechemical°2°=0signifiesthatthereactiondoesnot=1molindicatesthatthechangeofsubstancesequalsexactlytheirstoichiometricIII.III.Statedescriptionofchemical(化学反应体系的状态描述Systemo ureForchemicalreactionaA+bB=gG+hH, thedeterminestherelationshipofdifferent tyundertheconsiderationofthereactionasaclosedsystem.Asaconsequence,thethermodynamicstatecanbedescribedbyT，p，.Ifthereactionreachesequilibrium,itneedsonlySystemcontainingRindependentThethermodynamicstatecanbedescribedbyequilibrium,itneedsonlytwoparametersT，p. tiesofreactionsystems(化学反应体系的摩尔微分热力Molarenthalpyofreactionofpurereactantstopureproducts 0= BB= AA+ BB+GG+ AtstateofT，P，，thechangeofenthalpyofthechemicalreactionsystemwillbe )=nBH*m(B,T,p)=(nB+B)H*m(B,T,p)isthemolarenthalpyofpuresubstancesatT，p.AtstateT，P，+d，theenthalpyofthechemicalreactionsystemisH(T,p,+d)=[nB+B(+d)]Whenitproceedsfrom +d，thechangeofenthalpyofthechemicalreactionsystemisdH= +d)– )= BThisisatconstantT，ptheformulaofenthalpychangeofthechemicalreactionsystem,itisgenerallywrittenasrHm]T,p=BH*

（J.mol-rHmisthemolarenthalpyofchemicalreactionsystem.Itisanintensive tyofchemicalreactionsystem,andastatefunction.rHmdeendsonthe towritetheeuation应时的H=-1200J,对不同反应式计算积分摩尔焓变H/反应式1CO2aq

2MnO(aq)

H(aq) 2CO2(aq)

2Mn2(aq)5

85H反应式:52O4反应式:52O4 (aq)O4(aq)16H )→10CO(aq)2Mn2(aq)8H22

n(CO2)-0.162510-

- n(MO)-0.082010-3 n(CO2

2 n(MO (M

2 5

H n(CO2

300KJ.mol-

(CO2

H

1500KJ.mol-MolarenthalpyofreactionofmixturerHm]T,p=B

（J.mol-Itissimilartotheformulaofmolardifferentialenthalpychangeofpuresubstancereactants，butHm(B,T,pisthepartialmolarenthalpy(偏摩尔焓)ofsubstanceB,i.e.,H(B,T,p)HB

CIngeneral，themolardifferentialchangeofany tyL（=V，U，H，S，F，G，CV， ）ofth chemicalreaction0=BBcanbewrittenasrLm]T,p=BPartial ty(偏摩尔量ofsubstanceL(B,T,p)

LB BT,

Ccanbeexpressedusinganequationofchemicalcountingnumberof1:B(T,p,nB,…)=Themolarenthalpyofphasechange

Hm=[——]T,p=HB(T,p,nB,…)-HB(T,p,nBIfitconcernsaphasechangeofpure

Hm3.Themolarenthalpyof3.Themolarenthalpyofphasechangesubstance(物质的摩尔微分相变焓 omphasetomMolarMolarenthalpyofphysicalevaoration，fusionandMolarenthalpyofevaporation摩尔汽化焓gH*Molarenthalpyoffusion(摩尔熔化焓) mMolarenthalpyofsublimation摩尔升华焓) vap

H2O(s):fusfus

=fus

ForachangeofpuresubstanceBinphaseintoBinsolution，itmaybewrittenasThemolarenthalpyofphasechangelHm=

（1）Molarinternalenergyandmolarenthalpy化学反 0BB e.g.,aA+bB=yY+BMolarinternalenergy摩尔热力学能［变 V.MolarchangeV.Molarchangeof ofchemicalreactionsystems化学反应体系的rHm

H ofAccordingGB3102.8-93，thepressureofStandardstateofgas(气体的标准态)：ThegasbehavesasperfectgasatT，pnomatteritispuresubstancegasorthegasinamixture.Standardstatesofliquidsolid)液体(或固体)的标准态)Theliquid(solid)istheliquid(solid)ofpuresubstanceatT，p,nomatteritispuresubstanceinacomposite.Note：TheTofthermodynamicstandardstatearbitrar.H ermodynamicdataowereobtainedatT＝298.15K.

Thermodnamicstandardstate prescribesonlythepressure,p＝100kPa，Tisartificial.However，thestandardthermodynamicdatawereoftenobtainedatT＝298.15K.Standardstateofgas(气体的标准态)：ItindicatesalwaysthepuregasBatTandpbehavingasaperfectgasregardlessofthatBisapuregasorBisinamixture.Standardstateofliquidorsolid液体(或固体)的标准态）：ItindicatestheliquidorsolidofpuresubstanceBatT，p,regardlessofthatBisliquidofapuresubstanceorBisinamixture.（3）Thestandardmolarenthalpyofreactions(化学反应的标准摩尔焓［变（3）Thestandardmolarenthalpyofreactions(化学反应的标准摩尔焓［变Standardmolarenthalpyofreaction反应的标准摩尔焓[变 mFor aA＋bB rHm(T)= Y T)＋z T－aHm(A,Phase,T)－bHm(B,Phase,T)Formula(1）and(2）dohaveno