3.2 The Functions F and G(2) S.J.T.U. Phase Transformation and Applications G:the Gibbs free energy The useful work that can be done by the system must be calculated exclusive of the P-V term. oW =oWre -Pdv =dU-Tds Integrating at constant temperature and pressure Wr =AU+PAV-TAS=A(U+PV-TS) =△(H-TS)=△G G-H-TS dF =-SdT-Pdv dG =-SdT +VdP SJTU Physical Chemistry of Materials Spring2005©X.J.Jin Lecture 5 property relationPhase Transformation and Applications S. J. T. U. SJTU Physical Chemistry of Materials Spring 2005 © X. J. Jin Lecture 5 property relation 3.2 The Functions F and G (2) G: the Gibbs free energy rev rev −=−= TdSdUPdVWW * δδ The useful work that can be done by the system must be calculated exclusive of the P-V term. Integrating at constant temperature and pressure GTSH rev TSPVUSTVPUW Δ=−Δ= −+Δ=Δ−Δ+Δ= )( ( ) * = −TSHG VdPSdTdG PdVSdTdF +−= = − −