Clapeyron方程推导的探讨

Studies on Deduction of Clapeyron′s Equation

以单组分体系液－ 气平衡为例对Ｃｌａｐｅｙｒｏｎ 方程进行了严格的推导。当该体系升温增压时，其液相和气相所发生的变化分别相当于其纯相的先等温加压后等压升温和先等压升温后等温加压的复合变化。于是，利用单组分均相体系的热力学公式就可以方便而准确地得出平衡共存的液、气两相的吉布斯自由能变。

Clapeyron′s equation is deduced strictly by considering the gas liquid phase in a system of one component. When heated, the gas and liquid will move to a new state with a higher temperature and a greater pressure. Such a change is equivalent to that of being heated at constant pressure and afterwards being compressed at constant temperature as a pure phase for the gas and to that of being compressed at constant temperature and afterwards being heated at constant pressure as a single phase for the liquid. In this way, the variations of Gibbs free energy of two phases in equilibrium can be obtained conveniently and correctly from the basic thermodynamic formulas used for the systems of one component and only one phase, and the problem of using incorrect independent variables during the normal deduction of Clapeyron′s equation is avoided.