恒温下(O△GOP)T=△V关系式的应用 S.J.T.U. Phase Transformation and Applications 在298K和1atm下，石墨为稳定态 298K 石墨(G)>金刚石(D) 己知：石墨和金刚石的标准生产热和标准熵为 0,1900J.mo1,5.73J.mol1.K-1,2.43J.mo1.K1 298K下石墨和金刚石密度为：2.22g.cm3,3.515g.cm-3 V,=12/3.515=3.414cm3.mo-1 'c=5.405cm3.mo1 Diamond g △2Gnm(298K,latm)=△Hm-TASm Graphite T=Constant =1900-298(2.43-5.73)=2883J.mo1>0 Po Equilibrium pressure a△G Pressure- ap =AV='o-'o<0 Figure 4.3 Specific Gibbs free energy versus pressure at con- stant temperature for graphite and diamond. SJTU Thermodynamics of Materials Spring 20u/ cx.J.Jin Lecture 8 Cnemical equllibriumPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 8 Chemical equilibrium 恒温下 (∂ΔG/∂P)T =ΔV 关系式的应用 在298K和1atm下，石墨为稳定态 已知：石墨和金刚石的标准生产热和标准熵为 0，1900 J.mol-1， 5.73 J.mol-1.K-1, 2.43 J.mol-1.K-1 298K下石墨和金刚石密度为：2.22 g.cm-3, 3.515 g.cm-3 <−=Δ= 0 ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂Δ∂ GD T VVV pG 298K 石墨(G) -> 金刚石(D) 2883)73.543.2(2981900 0 )1,298( 1 >⋅=−−= Δ Δ−Δ= − molJ m m STHatmKG m DG 3 1 414.3515.3/12 − VD = = ⋅molcm 3 1 405.5 − VG = ⋅molcm