利用芒硝矿生产的硫酸钠,含纯量大多数在99％以上,Cl~-离子含量甚微。用氯化汞容量法测定芒硝中微量Cl~-离子,方法较简单,但在Cl~-含量很少时,指示剂颜色变化不明显,终点变化不敏锐。导致测量误差增大。本文介绍用电位法测定Cl~-离子含量,只要Cl~-含量大于30微克,不论试液有色或混浊与否均能适用。 The use of sodium sulfate production of sodium sulfate, most of the purity of more than 99%, Cl ~ - ion content is minimal. The determination of trace Cl ~ - ions in mirabilite by mercuric chloride volumetric method is relatively simple. However, when the content of Cl ~ - is small, the color of indicator is not obvious and the end point change is not sensitive. Resulting in increased measurement error. This paper describes the determination of Cl ~ - by potentiometry, as long as the Cl ~ - content of more than 30 micrograms, regardless of the test solution is colored or cloudy or not can apply.