测定氯化物方法的改进  

Improvement on determination methods of chlorides

作　　者：吴双成 

机构地区：[1]甘肃皋兰县胜利机械厂,甘肃皋兰730200

出　　处：《无机盐工业》2007年第11期53-54,共2页Inorganic Chemicals Industry

摘　　要：摩尔法和佛尔哈德法测定氯离子时,由于氯化银对氯离子的吸附和氯化银能转化为硫氰酸银沉淀,使得滴定终点色泽变化不敏锐,分析结果准确度不高,精密度较差,常用硝基苯、邻苯二甲酸二丁酯、甘油、四氯化碳、1,2-二氯乙烷等试剂来改善滴定终点色泽变化的敏锐性。这些物质或者效果不理想,或者有毒,或者购买困难。介绍了用平平加系列或OP乳化剂系列的物质来代替硝基苯,达到了改善滴定终点色泽变化敏锐性的目的,提高了精密度和准确度,同时毒性小,易于购买,分析成本低。对硝基苯和聚氧乙烯型表面活性剂,从分子结构方面做了比较,解释了包藏氯化银沉淀的原理。The analytical results were not very accurate and precise when determining the chloridions by mol method and Volhard method, because the titration end - point had a bad color - changing due to the adsorption of silver chloride to chloridions as well as silver chloride can convert into the precipitation of silver thiocyanate. Generally, the reagents, such as nitrobenzene, dibutyl phthalate （DHP） , glycerin, carbon tetrachloride and 1,2 - dichloroethane would be used to improve the acuteness of color - changing at end - point of titration. However,these substances either had unfavorable effect or be poisonous or difficult to buy. This paper introduced using peregal or OP - emulsifier series materials to replace nitrobenzene and finally achieving the object of improving the acuteness of color - changing at end - point of titration. The accuracy and precision were therefore enhanced. Meanwhile, the substitute materials were characterized by low toxicity, easy to buy and low analytical cost. Furthermore, the comparison between nitrobenzene and polyoxyethylene surfactants was made in terms of molecular structure and the principle of silver chloride precipitation - coating was explained.

关 键 词：氯离子分析 改进 硝基苯 平平加 乳化剂OP 

分 类 号：TQ124.42[化学工程—无机化工]