2.1 Entropy as a State Function(5) S.J.T.U. Phase Transformation and Applications Isothermal reversible △UU=O+W=0 isothermal wP pav reversible 2 RT dV =-RTIn2 A.S= RTIn T T 2=RIn2 Reversible 2V SJTU Thermodynamics of Materials Spring2010©X.J.Jin Lecture 3 Second law IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 3 Second law I 2.1 Entropy as a State Function(5) U  QW  0 isothermal ln 2 2 2 2 dV RT V RT W P dV PdV V V V V V V external                  Reversible reversible ln 2 ln 2 R T RT T Q S rev     Isothermal reversible