热力学第一、二定律试题及答案

5．

证明：其它合理证明也给分?S???S???S???V? ??????????????T?T?V?T??P??V??T??p??S???S?Cp?T?，CV?T??? ?T?T??P??V???S? ??S???Cp?CV?T????????T?T????V?P?

??S???V????? T???V?T??T?p??p???V??T???? ??T?V??T?p

四、计算题答案 1．解：

Qp = ΔvapHm= ·mol W = ΔvpaUm= kJ·mol

ΔvapGm = 0 ΔvapFm = kJ·mol ΔvapSm = J·K·mol 2． 3

θ

-1

-1

θ

θ

-1

θ

-1

θ

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(1)?rSm?13.42J?K?1?mol?1(2)?S环?134.2J?K?1?mol?1............?S隔?147.6J?K?1?mol?1(3)?G??44000J...............Wf,max???G?44000JQR?0，?S体?0,?S环?0，?Siso?0T2?497.5K.........W??4142J............?U??W?4142J?H?5799J........?F??36720J...........?G??35063J

4

T2=

ΔU=- J W= J ΔH=-1135 J ΔS= J·k

S2= J·k ΔG=4085 J ΔF=4539 J

5. 7．

-1-1

?rHm?13838.7J?mol?1?S?0.4618J?K?18．

T2?207K ΔU= J ΔH =-1372 J W = J

ΔS = 0 ΔG = 5228J ΔF = 5777 J 9． 10．

?H??5.824kJ?S??21.33J?K?1?G??107.1J?F???107.3J(Wf,max)T,p???G?107.1J(Wmax)T???F?107.3JW?0?U?27835JQ?27835J??VapSm?87.2J?K?1?mol?1??VapGm?0

?S环??78.9J?K?1?S隔?8.3J?K?1?0故向真空蒸发为不可逆过程12．

W = 0 ΔU = ΔH = ΔS = J·K·mol ΔG = － 13． 14．

??rHm??290J?mol?1??rSm?0.67J?K?1?mol?1??rGm?92.21J?mol?1??rGm?0，表明298.2K时正交硫稳定。-1-1

?H?4157J?mol?1?S?7.33J?K?1?mol?1?Sm(473K)?135.66J?K?1?mol?1??Sm(673K)?142.99J?K?1?mol?1??G??27.95kJ?mol?1不能判断过程是否可逆。?rVm?1.03?10?6m3?mol?1无法实现正交硫向单斜硫的转变。 15．

解：T?368.5K??sHm(斜方)?100.848kJ?mol?1??sHm(单斜)?97.306kJ?mol?1???rH??sHm(斜方)??sHm(单斜)?3542J