粗盐的提纯实验中pH值的理论探讨

Theory Investigation on pH Value in Experiment on the Purification of Crude Salt

粗盐的提纯是无机化学中的一个典型实验,该实验涉及电子天平的使用、加热、溶解、常压过滤、减压过滤、蒸发浓缩、结晶和干燥等过程,对提高学生的化学基本操作有很好的锻炼作用。根据要求不同,在中学至大学的化学实验中都有开设。但是控制好滤液的pH值是非常重要的,否则制备的食盐中会有碳酸氢钠等物质存在,本文运用分布分数探讨了pH值对产品的影响,并对实验中出现的其他问题进行了探讨。

The experiment on the purification of crude salt is typical in inorganic chemistry. It includes many operation processes, such as the use of electronic balance, heating, the solution of sample, atmospheric and vacuum filtration, evaporation and concentration, crystallization and drying, etc. It is good for improving students operation skills. This experiment is offered for many students from high school and university according to demand. It is important to control pH value of filtrate for the preparation of pure salt. The effect of pH value on purification of crude salt was discussed by distribution fraction, and other problems in the experiment also were investigated.