Contents of Today S.J.T.U. Phase Transformation and Applications Review previous On Gibbs free energy Electrochemical Nomenclature Calculation of Cell voltage Direction of Reaction etc. SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 10 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 10 electrochemistry I Contents of Today Review previous On Gibbs free energy Electrochemical Nomenclature Calculation of Cell Voltage Direction of Reaction etc
5.1 THERMODYNAMIC ACTIVITY (2) S.J.T.U. Phase Transformation and Applications No Units 三 Reference state:temperature,pressure and physical form Standard state:pressure and physical form Gas:pure gas at one atmosphere Condensed mater:pure liquid or solid under one atmosphere CdG,-G,-G=RTn人-RTna dG,-G,-G;=RTIn P=RTIna, Ideal gas The fugacity of a condensed phase is equal to the fugacity of the vapor in equilibrium with it. The value of thermodynamic activity changes not only with pressure but also with composition SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 10 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 10 electrochemistry I 5.1 THERMODYNAMIC ACTIVITY (2) D i i i f f α ≡ i i i i i G G i RT ff =−= RTGGdG ln = lnα ∫ D D D i i i i i G G i RT PP =−= RTGGdG ln = lnα ∫ D D D Ideal gas No Units Reference state: temperature, pressure and physical form Standard state: pressure and physical form Gas: pure gas at one atmosphere Condensed mater: pure liquid or solid under one atmosphere The fugacity of a condensed phase is equal to the fugacity of the vapor in equilibrium with it. The value of thermodynamic activity changes not only with pressure but also with composition
5.2 CHEMICAL EQUILIBRIUM S.J.T.U. Phase Transformation and Applications bB+cC=dD+eE Expression for a chemical reaction OWron=AG=dGD+eGE-bGB-cGc GB =GB+RTInag AG=d(Gi+RT Inap)+e(Gi RTInag)-b(GB+RT Inag)-c(Gc+RT Inac) △G=△G°+RTIn J G=0 △G°=dG)+eGE-bGB-cG& Equilibrium constant d。 e J b △G°=-RTInm）)=-RTIn K SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 10 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 10 electrochemistry I 5.2 CHEMICAL EQUILIBRIUM + = + eEdDcCbB δ rev D E B −−+=Δ= GcGbGeGdGW C )ln()ln()ln()ln( D +=Δ RTGdG α D E ++ RTGe α E B +− RTGb α B C +− RTGc α C D D D D α +Δ=Δ ln JRTGG D D D D D D D E B C −−+=Δ cGbGeGdGG c C b B e E d D J αα αα α = B BB += RTGG lnα D α KRT α JRTG mequilibriu −=Δ ln ( ) −= ln D Equilibrium constant Expression for a chemical reaction ΔG 0 =
5.6 ELLINGHAM DIAGRAMS (4) S.J.T.U. Phase Transformation and Applications 101010410 1. 直线位置越低，元素与氧 化合的能力越大，相应的 7402w0 氧化物越稳定； 7 2. 位置在下的金属或元素可 以把较上面的金属从氧化 物中还原出来； 00-00 3. 炼铁过程，铁以下进入炉 渣，铁以上进入铁液，决 定何时加入配料。 期0-子，03 局限 202…2g0 平衡的热力学讨论 1000 10-e 凝聚相都是纯物质 Figure 5.7 Ellingham diagram for some oxides. SJ I U Inermodynamics ot Materials Spring 2UU6 ©X.J.Jin Lecture 10 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 10 electrochemistry I 5.6 ELLINGHAM DIAGRAMS (4) 1. 直线位置越低，元素与氧 化合的能力越大，相应的 氧化物越稳定； 2. 位置在下的金属或元素可 以把较上面的金属从氧化 物中 还原出来； 3. 炼铁过程，铁以下进入炉 渣，铁以上进入铁液，决 定何时加入配料。 局限 平衡的热力学讨论 凝聚相都是纯物质
5.7 VARIATION OF EQUILIBRIUM CONSTANT WITH TEMPERATURE S.J.T.U. Phase Transformation and Applications d(△G)=-△SdT △G°=△H°-T△S dAG)=△Cdr- H°dr T T Multiplying by 1/T,we obtain: T aag)=a-RInK.）)=AHrd宁） SJTU Thermodynamics of Materials Spring2006©X.J.Jin Lecture 10 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 10 electrochemistry I 5.7 VARIATION OF EQUILIBRIUM CONSTANT WITH TEMPERATURE Multiplying by 1/T , we obtain: dTSGd D D )( Δ−=Δ D D D Δ−Δ=Δ STHG dT T H dT T G Gd D D D Δ − Δ )( =Δ dT T H dT T G T Gd 2 2 )( D D D Δ −= Δ − Δ ) 1()ln()( T dHKRd TG d D D Δ=−= Δ α ) 1 )(ln (T d RH Kd D Δ α −= G 1 d( ) H d( ) T T Δ = Δ D D