級(jí)物理化學(xué)-4、參考已雙語eng sgwhk

Generalizedchemical aA+bB=gG+0=B 0=AA+BB+GG+B-ChemicalformulaofB-Stoichiometricnumber:Reactant“–”;product nB–Theextentof

B

(B=A,B,G,StatedescriptionofchemicalSystemofpurereactantstopureT，p，；AtequilibriumonlySystemcontainingRindependentT，p，1，2，3，……R；Atequilibriumonly MolardifferentialchangeoftiesforchemicalreactionsystemsMolardifferentialenthalpychangeforreactionofpurereactantstopureproductsrHm]T,p=BH*

（J.mol-2MolardifferentialenthalpychangeforreactionofmixturereactantsrHm]T,p=B

（J.mol-Itissimilartotheformulaofmolardifferentialenthalpychangeofpuresubstancereactants，butHm(B,T,p)isthepartialmolarenthalpy(偏摩爾焓)ofsubstanceB,i.e.,H(B,T,p)

HB T,

C3MolardifferentialphasechangeenthalpyofSubstanceBundergoingachangefromphasetophasecanbeexpressedusinganequationofchemicalcountingnumberof1:B(T,p,nB,…)=Themolardifferentialenthalpychange

Hm=[——]T,p=HB(T,p,nB,…)-HB(T,p,nBIfitconcernsaphasechangeofpuresubstance,theHmisreplacedbyHm*4（4）Equationofthermochemistry:Theequationofchemicalreactionforwhichthereactionconditions,suchasT，p，existingstate,enthalpychange,etc.,havebeenindicated.Forexample,2C6H5COOH（s,p,298.15K)＋15O2(g，p,→6H2O（l,p,298.15K）＋14CO2（g,p J5（5）Hess(orecclaw蓋斯Themolarchangeofthermodynamic tyofaoverallreactionisthealgebraicsumofthemolarchangeofthermodynamictiesoftheindividualreactionsintowhichareactionmay

BrHm(T)=rHm,1(T)RIfAisthealgebraicsumofRreactions,thegeneralformofHesslawwillbe

ALmi6-6thRegulatedthermodynamic mCalculationofstandardmolarenthalpy(change)ofreactionrH (T)m(反應(yīng)的標(biāo)準(zhǔn)摩爾焓［變①CalculationofrH(T)frommmolarenthalpy(change)offormationsubstanceBfH(B,phase,T)(物質(zhì)B的標(biāo)m摩爾生成焓［變7Definition1：Reactionof0EEEEElementatitsmoststablestateBproduct,Definition2：Thestandardmolarchangeof tyofformationofasubstanceBequalsthestandardmolardifferentialchangeof tyofthereactionofformationofsubstanceB.L(T)L(T

H(T)H(T 8Thermodynamicstandardstate熱力學(xué)標(biāo)準(zhǔn)態(tài))prescribesonlythepressure,p＝100kPa，Tisartificial.However，thestandardthermodynamicdatawereoftenobtainedatT＝298.15K.Standardstateofgas(氣體的標(biāo)準(zhǔn)態(tài))：ItindicatesalwaysthepuregasBatT，pbehavingasaperfectgasregardlessofthatBisapuregasorBisinamixture.9Standardstateofliquidorsolid(液體(或固體)的標(biāo)準(zhǔn)態(tài)）：Itindicatestheliquid(orsolidofpuresubstanceBatT，p,inregardlessofthatBisliquidofapuresubstanceorBisinamixture.Theenthalpy(change)offormationofasubstanceBisnottheabsoluteenthalpyvalueofthesubstance,itistherelativeenthalpyversustheenthalpyoftheelementstoformit.SomeimportantThereactantissinglesubstanceatitsmoststableAtT=298.15KandpthemoststablesinglesubstancesCarbon-Graphite()Sulfure- Diamond()

--H

-OExample1.ReactionofformationofC（Graphite，298.15K，p）＋O2（g，298.15K，p＝CO2（g，298.15K，p H（298.15K）=-393.513kJ.mol H（CO，g，298.15K）= Example2.Reactionofformationof1/2H2（g，298.15K，p）＝H（g，298.15K，p H（298.15K）=217.940kJ.mol H（H，g，298.15K）=217.940kJ.mol Thestandardmolarenthalpyofformationofstablesinglesubstanceatstandardreferencestateiszeroforanytemperature.SuchasH(C，Graphite，T）＝0 Example3.ThereactionofformationofN2(g) H（298.15K）=0kJ.mol H（N，g，298.15K）= Thestandardmolarthermodynamic tyofformationisdefinedbythestandardmolardifferentialchangeofthermodynamic tyofaspecifiedreaction(reactionofformation).Itisstilladifferenceofthermodynamic ty,andisnottospeculatethethermodynamic tyofstablesinglesubstanceaszero.So,whenthestandardmolarenthalpyformationofBisgiven,itgivesinfacttheequationofthereactionofformationofBandthestandardmolarenthalpychange.CalculaterH(T)fromH(B,Phase,T PRPREf fECommonpoint：StablesinglesubstancerH（T）=H- For 0BB

H

H(B,phase,T

andHess We rH(T)= m rm

(298.15K)=

(B,Bfm aA(g)＋bB(g)Bfm rH(298.15K)=yH(Y,g,298.15K)＋z －afHm(A,g,298.15K)－bfHm(B,②CalculationofrHm(T)fromtheolaetalp b,tanceDefinitionofstandardmolarenthalpyofcombustionofsubstanceB,cHm (B,phase,T)Reactionof

OO0B OO

PPInaboveformula，BandO2arereactants(B=-1)，andtheyaremoststablesingleelements；Pisproduct，andisthecompletecombustionsubstance.Thesubstancesintheformulaareeithermoststablesingleelementoroxide Completecombustionmeans：（e.g.,atCCO2(g)；H2H2O(l)；N2NO2(g)；SSO2C(graphite)+O2(g)=CO2(g)H2(g)+1/2O2(g)=H2O(l)H2(g)+1/2O2(g)=H2O(g)

enthalpyofFormationenthalpyofStandardmolarcombustion

CH(B,Tm(標(biāo)準(zhǔn)摩爾燃燒焓)ItisthestandardmdifferentialenthalpychangeofthecombustionreactionofsubstanceB.Constant C

(B,T,pmConstant (B,T,VReactionH2(g)+1/2O2(g)=H2O(l)canbeconsideredeitherasthereactionofcombustionofH2，orasthereactionofformationofH2O(l).Suchas，cH(C,graphite,298.15K)isthesimplifieddescriptionofStandardmolardifferentialenthalpychangeofthereactionbelow： f [CO(g),298.15K]= Atstandardstate,thestandardmolarenthalpyofcombustionofH2O(l)，CO2(g)iszeroatanytemperature.mCalculationofrm

(T)fromc

(B,phase,T

H

H(B,phase,T

andeccm m We r (T)＝－ PRmrHPRm

H

H CommoncompleteoxidationrHm(T)=cHR-cHP=-(cHP-c Asfor aA(s)＋bB(g)mrm

(298.15K)＝－[yc

(Y,s,298.15K)＋zc

mmm－acHm(A,s,298.15K)－bc mmmExample：known H(CO H

O,l,298.15K)=-285.838KJ.mol- EvaluateSolution：Thereactionofcombustionof

C6H6(l)

2O2

6CO2(g) H Thereactionofformationof C(graphite)O2(g)CO2(g) HHCO,gThereactionofformationof

H(g)1O(g)HO

HHHO,l

Thereactionofformationof 6C(graphite)3H2(g)C6H6

HHCH,l Fromabove,we (2)6+(3)3–(1)=

H(CH,l,298.15K)=H =6H(CO,g,298.15K)+3 - (C6H6,l,298.15K)=49.03kJ.mol-CalculationofrH(T)fromenthalpymmbond鍵焓Bandenthalpyofatomization（原子化）aH(i)mEnthalpyofbond(鍵焓)：Itistheenthalpychangeofbreakingchemicalbond,atconstantpressure,toformvaporizedatomsorgroups.Inmolecularspectroscopythedissociativeenergyofabondsignifiestheenergytobreakthisbondinagivensubstance,whileinthermodynamicstheenthalpyofbondrepresentstheaverageenergyrequestedtobreakakindbond H2O(g)=H(g)+OH(g)H=502.1kJ.mol-1OH(g)=H(g)+O(g) H= H-O=H(H-O,298.15K)=(502.1+423.4)/2=462.8kJ.mol- CH4CH3+(dissociationCH3CH2+CH2CH+CHC+

iCi

4mEnthalpyofatomizationaH (i原子化焓)：Itistheheateffectfortheformationof1molvaporizedatomsfromsinglesubstanceatconstantpressurem1°CalculationofrHm(T)fromrHm(T)=1Hm-

rHm(T

=-B

Vaporized2°CalculationoffHm(T)fromaHm(i

(B)=

H+H

(TmBm =iaHm(i)-iA-

2H=-i

VaporizedExample：Evaluatethereactionheatofthe2C1O(g) CH H2HC,298.15KHO,298.15K6H H298.15K H H298.15K H HHiHi HA Molarenthalpyofdissolution摩爾溶解焓)andmolarenthalpyofdilution(摩Molarenthalpyofdissolving(摩爾溶解焓AtconstantTandp,anunit tyofsolutesubstanceB+solventA→solution（xB＝0.1）solHm（B,xB＝0.1）Molarenthalpyofdilution(摩爾稀釋焓AtconstantTandSolution(b1，containing tyofsolute+thesamesolvent→solutiondilHStandardenthalpyofformationofionsinaqueoussolution水溶液中離子的Prescription：TheenthalpyofformationofH+inunlimiteddilutingsolutioniszero,whichservesasstandard.Withthisprescription,wemayobtainstandardenthalpyofformationofanyionsReactionofformationof112H2(g)aq mfH(H,aq,298.15K)mH+(aq)+OH-(aq)= H H(i,298.15K Class

B等于CO生成

等于CO2生成298K時(shí)，石墨的標(biāo)準(zhǔn)摩爾生成焓 (C大于 等于

小于 不能確ThetemperaturedependenceofFor

0

H

rHm

T,

BHm(B,T,p,rHm

H H

Cp

T

T

BCp,B,mr p

p,T,

T,C

Cp,B

p

p,B

B

T,

T,

T,

T,Partialisobaricmolarheat

Molarchangeofisobaricheatcapacity摩爾WeobtaintheKirchhoff’s（rHm/T)p,=rCp,m=BTheintegratedformisoftenusedinpracticalH

)H(T) T2

1 1

IfCp,m=a+bT+cT2issuitableforallThemolardifferentialchangeofisobaricheatcapacitywillthenbe2Cp,mabTc2Forreaction0=BB,wea=b=c=

1/2 150CH5Cp( 1 1

)1C(Op 2p 2

H2O(g)H4vaporationPuretemperature

H2O(l)H3298Cp 1/2 25C H(HO,298K H(423K)H

H

H4HCalculationofheatofnon-isothermalprocesses1°ThehighesttemperaturethatcouldbereachedincombustionAdiabatic,constantH A+B CHQp=

Constant

C+H=H1+

Constantp,1T1T

H2

Cp,C Cp,D 2°ThehighesttemperatureorpressureforanexplosionofabombT1p1A+B C+U=Qv=

Constantp,U1=H1-

T1p1C+U=U1+

ConstantV,rising,1T1T

U2

pmax

T

TD

VC

dpV pV

VThepressuredependenceof H

H

H

V m

VT

T

pT,p

TTTT

pT

T

V

V

VB

nB VT

T

B BT,

T,

TVB,m

Partialmolar(偏摩爾體積B p,

BVB,mVTV

Molardifferentialrr

p,

change(摩爾微分體積變V

V T

T

p,

T,p T,

prHm

VB,m

V

B

T

rVT

T

p,

p, V Fromp1top2，rHm(p2)rHm(

) rVT Somespecific

Tp,rHm1°Pureperfect

T2°Condensedmatters，theexpansioncoefficientisVTV

VTV

TrHm

T

3°Realgas，usingtheequationof Relationshipbetween(H/)T,pand（U/)T,VFrom

dUU

dTU

dVU T

V

VdVV

TdTV

TdpVFrom

T

p

T

T,

U V

V

U

V dU

T

V T

V

p dp

V

T,

p,

T,

T

T

T,

T,pFrom

dUU

dTU

dpU T

p

T

T,HUUVpVT,We

U

UV

V T,

T

T,