重铬酸钾滴定法测定海绵铁中金属铁

Determination of Metallic Iron in Sponge Iron by Potassium Dichromate Titration Method

利用金属铁易溶解于三氯化铁,而铁的其他化合物不溶解的特性[1]。试样以三氯化铁溶液选择性地使金属铁则被氧化为二氯化铁于试液中,然后过滤不溶解的试样残渣。滤液用硫磷混酸酸化后,以二苯胺磺酸钠为指示剂,用重铬酸钾标准溶液直接滴定海绵铁中金属铁的含量。通过试验,总结出用FeCl_3溶解MFe,重铬酸钾滴定法分析MFe的方法及要点理论探讨。

By using the characteristics that the metallic iron is easy to dissolve in ferric chloride,while others of iron compounds are insoluble in ferric chloride. The specimen was added into ferric chloride solution to selectively make the metallic iron be oxidized into ferrous chloride existing in test solution,and then the insoluble residues of specimen were filtered out. Now,the filtrate was acidulated with sulfur phosphorus mixed acid,and taking diphenylamine sulfonate as an indicator,the content of metallic iron in the sponge iron was directly titrated with potassium dichromate standard solution. Through the experiments,the methods for dissolving MFe with Fecl_3 and analyzing MFe by potassium dichromate titration and the corresponding key points were summarized in the paper.