2.9 Entropy Changes(2) S.J.T.0. Phase Transformation and Applications 变化过程的 熵很重要， 所以要计算 H=AH △H= C Temperature S= dT △S P(S) Temperature SJTU Thermodynamics of Materials Fall 2012 X.J.Jin Lecture 5 property relation
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © X. J. Jin Lecture 5 property relation 2.9 Entropy Changes (2) ∫ Δ = Tm T P S dT T C S 1 ( ) ∫ Δ = Tm T P l dT T C S 1 ( ) m m m T H S Δ Δ = Temperature Entropy ∫ Δ = Tm T H CP S dT 1 ( ) ∫ Δ = Tm T H CP l dT 1 ( ) ΔH = ΔH m Temperature Enthalpy 变化过程的 熵很重要， 所以要计算
2.10 Entropy change in chemical reactions and the third law(1) S.J.T.0. Phase Transformation and Applications The calculation of entropy changes for a chemical reaction is similar to the calculation in the case of enthalpy changes. One very important difference: Nernst 1906 The entropy change in any chemical reaction involving only pure,crystalline substances: ZERO at the ABSOLUTE Zero of temperature. Pure:pure elements and stoichiometrically balanced compounds that are perfectly crystalline Planck The entropy of a pure,perfectly crystalline substances ZERO at the ABSOLUTE Zero of temperature. Superscript zero:standard state,1 atm △D =0 Subscript zero:temperature ZERO SJTU Thermodynamics of Materials Fall 2012 X.J.Jin Lecture 5 property relation
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © X. J. Jin Lecture 5 property relation 2.10 Entropy change in chemical reactions and the third law (1) The calculation of entropy changes for a chemical reaction is similar to the calculation in the case of enthalpy changes. One very important difference: Nernst 1906 The entropy change in any chemical reaction involving only pure, crystalline substances: ZERO at the ABSOLUTE Zero of temperature. Pure: pure elements and stoichiometrically balanced compounds that are perfectly crystalline. Planck The entropy of a pure, perfectly crystalline substances: ZERO at the ABSOLUTE Zero of temperature. 0 0 ΔS0 = Superscript zero: standard state, 1 atm Subscript zero: temperature ZERO
2.10 Entropy change in chemical reactions and the third law(2) S.J.T.0. Phase Transformation and Applications The third law provides a great simplification in the calculation of entropies of reaction Ag-A心+f9an-f9n The entropy changes near room temperature are often needed in thermodynamic calculations, the integral in above equation has been evaluated for many substance at 298 K. 298 S98= △H+了 -dT 0 T SJTU Thermodynamics of Materials Fall 2012 X.J.Jin Lecture 5 property relation
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © X. J. Jin Lecture 5 property relation 2.10 Entropy change in chemical reactions and the third law (2) The third law provides a great simplification in the calculation of entropies of reaction. ∫ ∫ Δ = Δ + = T P T P T dT TC dT TC S S 0 0 00 0 The entropy changes near room temperature are often needed in thermodynamic calculations, the integral in above equation has been evaluated for many substance at 298 K. ∫ ∫ ∫ + Δ + + Δ = + 298 0 0 298 b b m m T P T T b P b m m T P dT T C T H dT T C T H dT T C S
Index of nomenclature S.J.T.0. Phase Transformation and Applications Helmholtz free energy(F):亥姆赫茨自有能 Gibbs free energy(G):吉布斯自有能 Chemical potential:化学位 SJTU Thermodynamics of Materials Fall 2012 ©X.J.Jin Lecture 5 property relation
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © X. J. Jin Lecture 5 property relation Index of nomenclature Helmholtz free energy (F): 亥姆赫茨自有能 Gibbs free energy (G): 吉布斯自有能 Chemical potential：化学位 Index of nomenclature
Chap 3 Property Relations S.J.T.0. Phase Transformation and Applications The First Objective:to explore the variation of the energy functions(U and H) with temperature and pressure. The heat capacities(Cp and Cv)give the change of U and H with temperature, at constant volume and constant pressure,respectively. The Second Objective:to examine the dependence of properties,such as the internal energy,enthalpy,entropy,and other thermodynamic functions,on temperature,pressure,specific volume,and other intensive variables. P SJTU Thermodynamics of Materials Fall 2012 ©X.J.Jin Lecture 5 property relation
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © X. J. Jin Lecture 5 property relation Chap 3 Property Relations The First Objective: to explore the variation of the energy functions (U and H) with temperature and pressure. The heat capacities (Cp and Cv) give the change of U and H with temperature, at constant volume and constant pressure, respectively. The Second Objective: to examine the dependence of properties, such as the internal energy, enthalpy, entropy, and other thermodynamic functions, on temperature, pressure, specific volume, and other intensive variables. 2 1 B A V T T V U ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ T V U ⎟⎠⎞ ⎜⎝⎛ ∂∂ 2 1 B A P T P T H ⎟⎠⎞ ⎜⎝⎛ ∂∂ T P H ⎟⎠⎞ ⎜⎝⎛ ∂∂