物理化学(II)
(PHYSIVAL CHAMISTRY) (12)
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封闭系统的热力学基本关系式
对于封闭系统
dU = δQ δW
若是可逆过程
若w'=0 将U=H-pV代入 将U=A+TS代入 将H=G+TS代入
= TdS pdV w'
dU = TdS pdV
dH = TdS + Vdp
dA = SdT pdV
dG = SdT + Vdp
Gibss Equations Gibss Equations2
适用条件: (1) 封闭系统,w'= 0的任意可逆过程 (2) 组成不变,均相封闭系统中,w'=0的任意 过程(无相变和化学反应的可逆与不可逆 过程)
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应用: (1) 计算单组分,均相系统的状态函数的变化 例:对理想气体等温过程
dG = Vdp G = ∫
p2 p1
p2 Vdp = nRT ln p1
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(2) 导出许多有用的热力学关系式 ①
U H )V = ( )p T =( S S A U ) S = ( )T p = ( V V H G ) S = ( )T V =( p p A G S = ( )V = ( ) p T T
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② Maxwell equations
若
dz = Mdx + Ndy M N ( )x = ( )y y x
T p ( )V = ( )S V S S V ( )T = ( )p p T
V T ( )p = ( )S S p S p ( )T = ( )V V T
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③ 内能和焓随压力,体积的变化
dU = TdS pdV
U S ( )T = T ( )T p V V
p U ( )T = T ( )V p (Internal pressure) T V S H dH = TdS + Vdp ( )T = T ( )T + V p p
H V ( )T = V T ( ) p p T
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④ 热容随压力,体积的变化
H ( )T = ( ) p p T T T H = ( )T T p p
= T V V T ( ) p T p
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C p

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