化工熱力學(xué)答案3章

1、131.物質(zhì)的體積膨脹系數(shù)和等溫壓縮系數(shù)的定義分別為：，。試導(dǎo)出服從?k1PVVT??????????1TVkVP??????????VerWaals狀態(tài)方程的和的表達(dá)式。?k解：Vanderwaals方程2RTaPVbV???由Z=f(xy)的性質(zhì)得1yxzzxyxyz????????????????????????????1TPVPVTVTP????????????????????????????又??232TPaRTVVVb???

2、????????VPRTVb??????????所以??2321PaRTVVbVTRVb???????????????????????????3232PRVVbVTRTVaVb????????????故????22312PRVVbVVTRTVaVb??????????????????222312TVVbVkVPRTVaVb??????????????32.某理想氣體借活塞之助裝于鋼瓶中，壓力為34.45MPa，溫度為93℃，反抗一恒定的

3、外壓力3.45MPa而等溫膨脹，直到兩倍于其初始容積為止，試計(jì)算此過(guò)程之、U?、、、、、、Q和W。H?S?A?G?TdS?pdV?解：理想氣體等溫過(guò)程，=0、=0U?H?∴Q=W==2109.2Jmol21112ln2VVVVRTpdVpdVdVRTV??????∴W=2109.2Jmol又理想氣體等溫膨脹過(guò)程dT=0、PPdTVdSCdPTT??????????PVRTP?????????∴RdSdPP??∴=5.763J(molK)

4、222111lnlnln2SPPPSPSdSRdPRPR?????????=3665.763=2109.26J(molK)AUTS?????=2109.26J(molK)GHTSA???????=2109.26J(molK)TdSTSA?????=2109.2Jmol21112ln2VVVVRTpdVpdVdVRTV??????33.試求算1kmol氮?dú)庠趬毫?0.13MPa、溫度為773K下的內(nèi)能、焓、熵、、和自由焓之值。VCpC假

5、設(shè)氮?dú)夥睦硐霘怏w定律。已知：3(2)理想氣體由300K、0.1MPa到500K、10MPa過(guò)程的焓變和熵變21500362130031.69610.144104.03810TigpTHCdTTTdT???????????=7.02kJmol215003621300110ln31.69610.144104.03810ln0.1igTpTCPSdTRTTdTRTP?????????????=20.39J(molK)(3)500K、10MP

6、a的理想氣體轉(zhuǎn)換為真實(shí)氣體的剩余焓和剩余熵Tr=T2Tc=500417=1.199Pr=P2Pc=107.701=1.299—利用普維法計(jì)算01.60.4220.0830.2326rBT????02.60.6750.4211rrdBTdT??14.20.1720.1390.05874rBT????15.20.7220.281rrdBTdT??又0101RrrrcrrHdBdBPBTBTRTdTdT?????????????????01R

7、rrrSdBdBPRdTdT??????????代入數(shù)據(jù)計(jì)算得=3.41KJmol、=4.768J(molK)2RH2RS∴=H2H1=H2==91.4170203410=3.701KJmolH?1RH1H?2RH=S2S1=S2==0.203720.394.768=24.95J(molK)S?1RS1S?2RS35.試用普遍化方法計(jì)算二氧化碳在473.2K、30MPa下的焓與熵。已知在相同條件下，二氧化碳處于理想狀態(tài)的焓為8377Jm

8、ol，熵為25.86J(molK).解：查附錄二得二氧化碳的臨界參數(shù)為：Tc=304.2K、Pc=7.376MPa、ω=0.225∴Tr=TTc=473.2304.2=1.556Pr=PPc=307.376=4.067—利用普壓法計(jì)算查表，由線性內(nèi)插法計(jì)算得出：??01.741RcHRT????10.04662RcHRT???00.8517RSR????10.296RSR??∴由、計(jì)算得：????01RRRcccHHHRTRTRT???

9、????01RRRSSSRRR???HR=4.377KJmolSR=7.635J(molK)∴H=HRHig=4.3778.377=4KJmolS=SRSig=7.63525.86=33.5J(molK)38.試估算純苯由0.1013MPa、80℃的飽和液體變?yōu)?.013MPa、180℃的飽和蒸汽時(shí)該過(guò)程的、V?和。已知純苯在正常沸點(diǎn)時(shí)的汽化潛熱為3.733Jmol；飽和液體在正常沸點(diǎn)下的體積為95.7H?S?cm3mol；定壓摩爾熱容