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前言铁的滴定分析法通常可分铈盐法、高锰酸钾法和重铬酸钾法三种,除了铈盐因价昂不常用以外,重铬酸钾要比高锰酸钾好得多。它的主要优点是:(1)容易制得纯粹,可用作原始标准,毋需标定。(2)它的溶液很安定。(3)它可在冷稀盐酸溶液中进行滴定,并无干挠影响。但重铬酸钾法和其他二种方法一样,在滴定前须先用还原剂还原Fe(Ⅲ)成Fe(Ⅱ)。常用的还原剂有二种:(1)汞齐化的锌粒,采用这种还原剂需要20—30筛孔的锌粒,这种锌粒价很昂贵;还原管须经常充满蒸馏
Preface Iron titration method can usually be divided cerium salt method, potassium permanganate method and potassium dichromate method three, with the exception of cerium salt due to price is not often used, potassium dichromate is much better than potassium permanganate . Its main advantages are: (1) easy to make pure, can be used as the original standard, without calibration. (2) Its solution is very stable. (3) It can be titrated in cold dilute hydrochloric acid solution without the effect of scratch. However, potassium dichromate method, like the other two methods, must reduce Fe (Ⅲ) to Fe (Ⅱ) with reducing agent before titration. There are two commonly used reductants: (1) amalgamated zinc particles, the use of this reducing agent requires 20-30 mesh zinc particles, the zinc price is very expensive; the reduction tube must often be filled with distillation