Micro Model Of Phase Transition And Saturated Vapor Pressure Equation

With the development of the technology of experiments and the theory of thermodynamics and statistical physics,the corresponding experimental data are continuously improved,meanwhile the theory of phase transition has also been matured gradually.Because of the great significance,a series of models and theories about saturated vapor pressure were developed.In the phase transition,when the two phases maintain a dynamic equilibrium,each thermodynamic parameter takes a fixed value,of which the saturated vapor pressure is an important parameter that describes the phase transition equilibrium.In this paper,a micro model for evaporation or sublimation was proposed to study the saturated vapor pressure.And in this micro model,there is an interface layer composed of low-energy particles and high-energy particles;furthermore,particles of two energy levels have a specific energy level difference,and the high and low energy levels correspond to liquid(or solid)and gas molecules,respectively.We assume that the interface layer is in equilibrium,so the particle number ratio of these two energy-level particles can be determined by the two-level Boltzmann distribution law;therefore,the phase transition can be described as the transition of particles between the two energy levels,and the energy level difference is determined by the latent heat.Based on the micro model and the relevant experimental data,we determined the characteristics of the particle energy level difference,energy level particle ratio,and volume ratio in the interface layer;moreover,we derived the saturated vapor pressure equation.The equation is used to study the gas-liquid phase change,gas-solid phase change,and triple point of water.The saturated vapor pressure and the rate of change are calculated,which is consistent with the experiment ideal result.The equation is also used tostudy the saturated vapor pressures of several other pure substances,and ideal results are obtained,which shows that our microscopic phase transition model and the corresponding saturated vapor pressure equation have certain rationality and feasibility.