二组分体系气液平衡相图实验的再讨论与改进  

Design improvement of gas-liquid equilibrium phase-diagram experiment for binary systems

作　　者：孟超 MENG Chao(School of Materials Design&Engineering,Beijing Institute of Fashion Technology,Beijing 100029,China)

机构地区：[1]北京服装学院材料设计与工程学院,北京100029

出　　处：《实验技术与管理》2024年第6期200-205,共6页Experimental Technology and Management

基　　金：北京服装学院高水平教师队伍建设专项资金项目(BIFTXJ202221)。

摘　　要：在传统二组分体系气液相平衡相图实验中使用的沸点测定仪虽盛行多年,却暗藏一个未被关注而影响深刻的理论性设计缺陷,系统内由于气相冷凝液的产生使相数增加而违背了相律,冷凝水的温度对气相冷凝液的组成有明显影响。该文在理论和应用层面分析和探讨了原有装置存在的主要问题,重新设计了二组分体系气液平衡相图原位测试装置。该装置可实现对气相物质的原位监测而不需要产生气相冷凝液,能够消除传统实验在理论建立和测试应用中长期存在的矛盾点,解决物理化学实验教学中的这一问题,使实验装置符合实验原理,提高了实验精确度,可为物理化学实验仪器的开发提供借鉴。[Objective]The gas–liquid equilibrium phase-diagram experiment for binary systems is a fundamental experiment in physical chemistry,essential for understanding phase equilibrium.It is a classic experiment conducted in university physical chemistry courses.However,the experimental setup features hidden theoretical flaws in its design,contradicting fundamental principles of thermodynamics.Owing to the formation of gas-phase condensate,the actual number of phases in the device is three,failing to meet the condition of two-phase equilibrium.Additionally,no thermal equilibrium exists between the system and the environment.This paper presents an in-depth analysis of the scientific issues present in traditional experimental apparatus from the perspective of physical and chemical theory.[Methods]We conduct a theoretical analysis of the composition of gas-phase condensate in traditional experimental apparatus and reveal that true“phase equilibrium”is not achieved when the system contains three phases.Furthermore,we investigate the impact of condensation temperature on the composition of gas-phase condensate.The experimental results demonstrate that when the temperature of the heated liquid phase remains nearly constant at a specific value,the concentration of n-propanol in the gas-phase condensate is higher at a condensate water temperature of 5°C than at a temperature of 15°C.This highlights that the boiling point does not correspond to a specific composition ratio in the traditional experimental setup.[Results]Furthermore,this paper proposes an improved in situ testing experiment setup for gas–liquid equilibrium phase diagrams of two-component systems,which holds significant importance for experimental teaching and academic research.This new device model utilizes a four-way valve group to conduct in situ sampling and testing of gas-phase substances in the system,eliminating the need for gas-phase condensation.Consequently,the new setup enables in situ monitoring of gas-phase substances throughout the experimen

关 键 词：二组分 相图 气液相平衡 相律 

分 类 号：O645[理学—物理化学] O6-32[理学—化学]