ΔS=ΔS1+ΔS2+ΔS3+ΔS4=129.3J·K-1? 11、解: ΔS(体)=nΔ
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Hm?/T=87.1 J·K-1?
Q(实)=ΔU=ΔH-nRT=27797J ΔS(环)=-Q(实)/T=-78.5J·K-1 ΔS(总)=ΔS(体)+ΔS(环)=8.4J·K-1 ∵ΔS(总)>0 且环境不对体系做功 ∴该过程为自发过程 12、解:
ΔS1=nCp,m(l)ln(278.8/268)=4.87J·K-1? ΔS2=-nΔ
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Hm?/T=-35.61J·K-1?
ΔS3=nCp,m(s)ln(268/278.5)=-4.71J·K-1? ΔS(总)=ΔS1+ΔS2+ΔS3=-35.45J·K-1? ΔH(268K)=-9874J
ΔG(268K)=ΔH(268K)-TΔS=-373J 13、解:
设计过程并得出ΔG=ΔG1+ΔG2+ΔG3+ΔG4+ΔG5 ΔG2=0 ΔG4=0
ΔG1、ΔG5很小,ΔG1≈ΔG5,故可忽略 ΔG=ΔG3=nRTln(p2/p1)= -108J ∵ΔGT,p<0 ∴过程自发
ΔS(总)=ΔS(体)+ΔS(环)=2.3J·K-1) ∵ΔS(总)>0
∴该过程是不可逆过程 16、解: 设C6H6(g)为理气 W=RT=2.94kJ·mol-1 Q=ΔH=34.7kJ·mol-1
ΔU=Q-W=31.8kJ·mol-1 ΔS=ΔH/T=98.3J·K-1·mol-1 ΔG=0
ΔA=ΔG-pΔV=-2.94kJ·mol-1 17、解:
ΔS=nCp,m(H2O,l)ln(373.2/298.2)+nΔg)ln(473.2/373.2) =126.84J·K-1?
Sm? (473K,H2O,g)=ΔS+Sm? (298K,H2O,l)=315.5J·K-1·mol-1 ΔH=ΔH1+ΔH2+ΔH3+ΔH4=48.81kJ ΔG=ΔH-(T2S2-T1S1)=-44.21kJ 18、解: ΔS1=23.5J·K-1? ΔS2=108.8J·K-1? ΔS3=-10.6J·K-1? ΔS4=57.4J·K-1?
ΔS=ΔS1+ΔS2+ΔS3+ΔS4=179.5J·K-1? ΔH=ΔH1+ΔH2+ΔH3+ΔH4=44.47kJ ΔG=ΔH-TΔS=-4.27kJ 19、解:
ΔS=nRln(V2/V1)=11.53J·K-1 能用熵判据判断该过程的性质
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Hm?/373.2+ nCp,m(H2O,
ΔS(环)=-Q/T=0
ΔS(总)=ΔS(环)+ΔS(体)=11.53J·K-1 ∵ΔS(总)>0 且环境不对体系做功 ∴该过程为自发过程 20、解:
先求出终态的共同温度TK:
5000×0.502×(700-T)=14000×2.51×(T-294) T=321.07K
(1)ΔS(钢)=5000×0.502ln(321.07/700) =-1956.35J·K-1
(2)ΔS(油)=14000×2.51ln(321.07/294) =3095.11J·K-1
(3)ΔS(总)=ΔS(钢)+ΔS(油)=1138.76J·K-1? 21、解:
NH2CH2CONHCH2COOH+H2O—→2NH2CH2COOH ΔrSm?=-82.84J·K-1·mol-1 ΔrHm?=-43.30kJ·mol-1
ΔrGm?=ΔrHm?-TΔrSm?=-26927.56J·mol-1 22、解: ΔG=8584J
ΔA=ΔG-Δ(pV)=ΔG-nRT=6106J ∵ΔGT,p>0
∴液态水稳定 23、解:
W(体)=0 W(电)=91838.8J ΔU=Q-W=121796J ΔS=Qr/T=7196J·K-1? ΔA=-W(电)=-91838.8J ΔG=-W(电)=-91838.8J 24、解:
1000K时,ΔrGm?=3456.9J 又∵( ΔG/ T)p=-ΔS?
=-7.57-7.57lnT+1.9×10-2×2T-3×2.84×10-6T2-2.26 ∴ΔSm?=7.57+7.57lnT-3.8×10-2T+8.52×10-6T2+2.26 将T=1000K代入上式即得: ΔSm?=33.39J·K-1·mol-1
ΔHm?=ΔGm?+TΔSm?=36855.06J·mol-1 25、解:
(1)由T2=T1(V1/V2)γ-1??得T2=270K ΔS=Cp,mln(T2/T1)+Rln(V2/V1)=0 (2)T2=340K
ΔS=Rln(V2/V1)=5.76J·K-1