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本法使用混合还原剂将硫酸还原为硫化氢,蒸馏分离之后与N,N-二乙基对苯二胺生成蓝色亚乙基蓝进行比色测定。混合还原剂溶液:取分析纯氢碘酸300毫升,次亚磷酸80毫升,盐酸150毫升,于三角烧瓶中加热沸腾10分钟以上,冷后贮于棕色瓶中备用。显色剂溶液:称取N,N-二乙基对苯二胺硫酸盐5.2克,溶于500毫升1:1硫酸溶液中。标准曲线的绘制:称取预先在120℃干燥过的优级纯硫酸钾0.2842克,准确配制成500毫升溶液。然后,分别取此标液0、5.00、15.00、25.00、35.00、50.00毫升于6个50毫升容量瓶中,用水稀释至刻线。吸取第一份稀释液1.00毫升于50毫升圆底蒸馏瓶中,加入15毫升混合还原剂溶液,按图装配好仪器。接收瓶为100毫升容
This method uses a mixed reductant to reduce sulfuric acid to hydrogen sulfide. After the distillation and separation, blue color is determined with N, N-diethyl-p-phenylenediamine blue. Mixed reductant solution: Take analytically pure hydriodic acid 300 ml, hypophosphorous acid 80 ml, hydrochloric acid 150 ml, heated in an Erlenmeyer flask boiled for more than 10 minutes, cooled and stored in a brown bottle standby. Developer solution: Weigh 5.2 g of N, N-diethyl-p-phenylenediamine sulfate and dissolve in 500 ml of 1: 1 sulfuric acid solution. Draw the standard curve: Weigh 0.2842 grams of pure grade potassium sulfate previously dried at 120 ° C and accurately make 500 ml solution. Then, take this standard solution 0,5.00,15.00,25.00,35.00,50.00 ml in six 50 ml volumetric flask, dilute with water to the score. Draw the first dilution of 1.00 ml in a 50 ml round bottom distillation flask, add 15 ml of mixed reducing agent solution, assemble the instrument as shown. Receiving bottle is 100 ml capacity