Thermodynamic activity (4) S.J.T.U. Phase Transformation and Applications The change of Gibbs free energy upon mixing: Gre =Gi(solmion)-G(pue)=kTIn) fi=fP Grol=GI(sohuion)-G(pue)=RTInx; (ideal solution) di xi SJTU Thermodynamics of Materials Spring2oo6©X.J.Jin Lecture 12 Solution IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 12 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