ENG_sgwhk07 - Prescribed thermodynamic quantities Standard...

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1 Reaction of formation + = E E B E ν 0 Δ r H m Θ ( T ) = Σ ν B Δ f H m Θ (B,phase, T ) = B B B 0 For reaction Reaction of combustion + + = P P 2 O P O B 0 2 ( ) ,, rm B Cm B HH B T ΘΘ Δ= Δ phase Standard molar enthalpy of formation of substance B, Δ f H m Θ (B,phase, T ) standard molar enthalpy of combustion of substance B, Δ c H m Θ (B,phase, T ) Prescribed thermodynamic quantities We have
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2 m , p r m , B , p B p , T p p , T , p , p p , T , p m r C C C T H H T T H Δ = ν Σ = ξ = ξ = ξ = Δ ξ ξ ξ = Δ B , p m , B m , B B , T m r T V T V p H ξ ν m , p r T V T V Δ = p T T V T p T V V U p U H , , , , + = p , T m r H H = Δ p , T m r U U = Δ The temperature dependence of Δ r H m The pressure dependence of Δ r H m Relationship between ( H / ∂ξ ) T,p and U / ∂ξ ) T,V
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3 Chapter 2 The 2 nd law of thermodynamics ( 热力学第二定律 ) The 2 nd law of thermodynamics solves the problem of direction and limit of substance changing processes The direction Graphite ⎯→ Diamond (It could not be done at normal temperature and pressure The limit Benzene + Methane ⎯→ Benzoic methane + Hydrogen The transform ratio is only 0.1%) -7 th lecture-
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4 Spontaneous processes ( 自发过程 , Natural processes): The process can be achieved without an external agency having to do work on the system Non-spontaneous processes ( 非自发过程 ): The process could not be achieved unless an external agency has done work on the system.
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5 3.1 The spontaneous process has determinate direction and limit For all real macro processes they take place always from non-equilibrium to equilibrium, and stop at equilibrium; and they could not be happened from equilibrium to non-equilibrium.
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6 Examples ①热 Q 的传递 :高温 ( T 1 ) 低温 ( T 2 ), T 1 T 2 为止 , 反过程不能自发 ②气体膨胀 :高压 ( p 1 ) 低压 ( p 2 ) p 1 p 2 为止 , 反过程不能自发 ③水与酒精混合 :水+酒精 溶液,均匀为止 , 反过程不能自发 气体膨胀 自发 Q 递自发 混合均匀 自发 搅拌水作功 f 摩檫生热
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7 Process Direction limit Water flow Water level h 1 > h 2 h 1 = h 2 Heat transaction Temperature T 1 > T 2 T 1 = T 2 Gas expansion Pressure p 1 > p 2 p 1 = p 2 Electric charge flow Electric potential E 1 > E 2 E 1 = E 2 The direction and limit of spontaneous processes
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8 The common character of spontaneous processes is that
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This note was uploaded on 05/25/2011 for the course CHEMISTRY 001 taught by Professor Tian during the Spring '11 term at Xiamen University.

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ENG_sgwhk07 - Prescribed thermodynamic quantities Standard...

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