Liauid Vapor The change that occur whena pure substanceis heed nasealed tube of constant volume - 1)Subcooled liquidE 2)Subheated vaporG 3)mixture ofliquid and vapor J K pt 图 ● Q N (,K ●- H G-T T 3.1.6 Single-Phase Region For the regions where a single phase exists f(P,',T)=0 V=V(T.P) w-r)n) Forliquid Volume expansivity =】 Isothermal compressibility dv BdT-kdP Thinking(3-6)
The change that occur when a pure substance is heated in a sealed tube of constant volume 3.1.6 Single-Phase Region For the regions where a single phase exists Thinking(3-6) p T C V T1 TC C T2 p F E E F (J,K) H G N Q Vc 2 v V 1 v V 2 l V 1 l V J K N Q G H Vc V V T P = ( , ) P T V V dV dT dP T P = + Isothermal compressibility 1 P V V T 1 T V V P − Volume expansivity dV dT dP = − For liquid V L P T A B C S G L- S-GG S- L p T Liquid Vapor Solid C P1 1 l V 2 l V Vc 1 v V 2 v V 1）Subcooled liquid E 2）Subheated vapor G 3）mixture ofliquid and vapor J K f P V T ( , , ) 0 =
features of and for liquid? 3.2 Virial Equations of state 3.2.I Introduction to EOS For a pure substance F=1Fx=C-P+2=1-1+2=2 that is:For a pure substance.fixing two of its properties fixes all the othersand thus determines its T=o(P,V)or P=W(T,V)or V=5(P,T) f(P.V,T)=0- The equation ofstate(EOS) Value of EOS EOS的价值： 1)精确地代表相当广泛范围内的PT数据，大大减少实验测定工作量。 2)可直接计算不做实验测定的其它热力学性质 3)讲行相平衡的计算 但其通用性差，要在广泛的气体密度范围内即用于极性物质，又用于非极性物质，又要精 度，很难做到。 The necessary conditions of EOS 1)According with critical condition 2)P0().according with the law of ideal gas 3.2.2 Virial Equation of State The PIproduct for a gas or vapor may be expressed as a function of P by a power series s or The PI product for a gas vapor may be expressed as a function of Pby a power series plV=a+bP+cP2+. Let c9 T b=aB,c=aC,.p=a+Bp+Cp2+） Wherea.B',C',etc.,are a=RT constants foragiven temperature and a given chemical species 3.2.3 Two forms of the Virial Equation Compressibility factor RT
features of κandβfor liquid ? 3.2 Virial Equations of state 3.2.1 Introduction to EOS For a pure substance Fmax =? Fmax =C-P+2=1-1+2=2 that is: For a pure substance, fixing two of its properties fixes all the others, and thus determines its thermonadymic state We can write: Value of EOS EOS 的价值： 1）精确地代表相当广泛范围内的 PVT 数据，大大减少实验测定工作量。 2）可直接计算不做实验测定的其它热力学性质 3）进行相平衡的计算 但其通用性差，要在广泛的气体密度范围内即用于极性物质，又用于非极性物质，又要精 度，很难做到。 The necessary conditions of EOS 1）According with critical condition 2）P→0（V→∞）, according with the law of ideal gas 3.2.2 Virial Equation of State The PV product for a gas or vapor may be expressed as a function of P by a power series The PV product for a gas or vapor may be expressed as a function of P by a power series Let Where a , B′, C′, etc., are constants for a given temperature and a given chemical species 3.2.3 Two forms of the Virial Equation Compressibility factor T P V or P T V or V P T = = = ( , ) ( , ) ( , ) The equation of state (EOS) f P V T ( , , ) 0 = T1 p TC C T2 V 2 pV a bP cP = + + + ' ' b aB c aC = = , , ' ' 2 pV a B P C P = + + + (1 ) a RT PV Z RT