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液体饱和蒸气压测定实验的拓展与延伸

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液体饱和蒸气压实验通过测定一定温度区间内液体的饱和蒸气压,利用克-克方程得到摩尔蒸发焓.由于摩尔蒸发焓是温度的函数,不同温度区间其测定值不同,导致相对误差较大.结合摩尔蒸发焓的计算筛选温度区间以减小实验误差的方法未见应用于实验教学.本实验选择纯水代替有机试剂作为研究对象,根据基尔霍夫定律的方法计算不同温度区间水的平均摩尔蒸发焓,以此作参照确定最佳温度测量区间.进一步引入拉乌尔定律,将纯液体饱和蒸气压的测定扩展应用于电解质与非电解质溶液,可关联更多理论教学内容.实验结果表明,40–60℃范围内测定纯水的饱和蒸气压误差较小,利用实验结果得到的摩尔蒸发焓与计算值相吻合,误差仅为0.465%.将该方法拓展至蔗糖和NaCl溶液饱和蒸气压的测定,可以进一步验证拉乌尔定律以及非理想稀溶液引入活度因子的必要性.此外,利用虚拟仿真技术演示静态法中气体分子的流向和系统压力的变化,增加可视化效果,使实验原理清晰易懂.
Expansion and Extension of Liquid Saturated Vapor Measurement Experiment
The expansion and extension of the liquid saturated vapor pressure measurement experiment involves determining the saturated vapor pressure of a liquid within a certain temperature range and using the Clausius-Clapeyron equation to obtain the molar evaporation enthalpy. Since the molar evaporation enthalpy is a function of temperature, its values differ in different temperature ranges, resulting in relatively large relative errors. The method of selecting temperature ranges based on the calculation of molar evaporation enthalpy to reduce experimental errors has not been applied in experimental teaching. In this experiment, pure water is chosen as the research object instead of organic reagents, and the average molar evaporation enthalpy of water in different temperature ranges is calculated using the method of Kirchhoff's law, which serves as a reference to determine the optimal temperature measurement range. Furthermore, the determination of the saturated vapor pressure of pure liquid is expanded to electrolyte and non-electrolyte solutions using Raoult's law, which can be linked to more theoretical teaching content. The experimental results show that the error in measuring the saturated vapor pressure of pure water within the range of 40–60 ℃ is small, and the molar evaporation enthalpy obtained using the experimental results is in good agreement with the calculated value, with an error of only 0.465%. Expanding this method to the determination of the saturated vapor pressure of sucrose and NaCl solutions can further verify the necessity of introducing activity coefficients in Raoult's law and the importance of studying non-ideal dilute solutions. In addition, using virtual simulation technology to demonstrate the flow of gas molecules and the change in system pressure in the static method can enhance visualization and make the experimental principle clear and easy to understand.

Saturated vapor pressureClausius-Clapeyron equationRaoult's lawSucrose aqueous solutionNaCl aqueous solution

颜美、丰日达、叶尔多斯∙托合塔尔汗、龙彪、周丽、果崇申

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哈尔滨工业大学化工与化学学院,哈尔滨 150001

饱和蒸气压 克劳修斯-克拉贝龙方程 拉乌尔定律 蔗糖水溶液 NaCl水溶液

黑龙江省高等教育教学改革项目一般研究项目

SJGY20210302

2024

大学化学
北京大学 中国化学会

大学化学

影响因子:0.636
ISSN:1000-8438
年,卷(期):2024.39(3)
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