Thermodynamic activity (4) S.J.T.U. Phase Transformation and Applications The change of Gibbs free energy upon mixing: Grel=Goluion)-G(pue)=RTIn fi=fP Gro=Gi(sohuion)-G(pue)=RTInx; (ideal solution) ai xi SJTU Thermodynamics of Materials Spring 2007 ©X.J.Jin Lecture 11 Solution IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 11 Solution I Thermodynamic activity (4) The change of Gibbs free energy upon mixing: )( )( )( )( ln purei solutioni pure solutioni rel f f GG =−= RTG pure i solutioni rel = GG )( )( =− ln xRTG (ideal solution) p i i = ff D D i i i f f α ≡ ii α = x