二组分体系水-正丙醇的气液平衡相图绘制

Gas-liquid Equilibrium Phase Diagram of Binary Liquid System Water and n-propanol

为探索物理化学绿色化实验室的建设,选用便宜、毒性小的水-正丙醇作为二组分体系,实验装置采用普通的沸点仪和酒精灯,通过逐渐添加法配置溶液,进行了该体系的气液平衡相图的绘制。总结了实验过程中应该注意的事项,得到了该体系的用不同浓度表示方法的2种t-x相图,相图中气相线和液相线相交之处有明显的相切特征。得到的该体系在常压下的最低恒沸点为87.2℃。浓度用摩尔分数表示时得到的相图的最低恒沸点位于整个相图的中间部分,明显好于用质量浓度得到的相图。该体系绿色无污染,结果稳定、可靠,是一个值得推荐的二组分体系。

To investigate into the construction of the ＂ green＂ laboratory of physical chemistry, the cheap and innoxious water and n-propanol were chosen as the binary liquid system. Using the common ebulliometer and alcohol burner, the drawing method of its phase diagram was explored. The solution was proposed using gradually-adding method. The key matters in the experiments were summarized. The phase diagram was obtained by using different representation of concentration. In the phase diagram, the characteristic of tangency of liquidus curve and gaseous curve was obviously observed. The lowest constant boiling point of the system was 87.2 C. When mole fraction was used for x-coordinate, the quality of the phase diagram was better than the one obtained by using mass concentration since the lowest constant boiling point is at the middle of the diagram. The system water and n-propanol is worthy of recommendation due to its non-pollution and stable results.