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我们研究了硫离子催化碘氧化迭氮酸的反应(1),注意到由于有反应(2)的同时存在, 致使 I_2+2N_3~- S~→=2I~-+3N_2(很快)(1) I_2+S~=——2I~-+S~0(较慢)(2)反应进行不长时间后,S~=全部被碘氧化,反应停止,但由于反应(1)的速度远超过反应(2),因此在这段反应期间内,微量硫离子的存在,仍将引起显著量的碘被迭氮酸还原,且发现碘的总消耗量与硫离子的初始浓度成直线关系。我们采用比色法和双铂电极电流测量法测定碘的浓度,拟定了高度灵敏的测定硫的方法。用该法测定硫的范围可从3××10~(-5)M到1.5×10~(-9)M,测定值的平均偏差不超过±10％,且操作从容简捷,结果的重现性较以往之动力学方法,也显著提高。 我们研究了溶液的pH、各试剂浓度、温度、零价硫及一些外来离子对反应中碘消耗量的影响;还利用所拟定的方法测定了金属镍及锰钢中负二价硫的含量,并用测定硫回收量的办法考核了方法的可靠性,结果都令人满意。
We studied the reaction of sulfur ion catalyzed iodine oxidation of azonic acid (1), noting that due to the simultaneous presence of reaction (2), I 2 + 2N 3 ~S ~ → = 2I ~ - + 3N 2 ) I_2 + S ~ = - 2I ~ - + S ~ 0 (slower) (2) After the reaction is not carried out for a long time, all of S ~ = is oxidized by iodine and the reaction is stopped. However, since the reaction (1) (2), the presence of trace sulfur ions will still cause a significant amount of iodine to be reduced by the azodic acid during this period of reaction, and the total consumption of iodine is found to have a linear relationship with the initial concentration of sulfide ions. We use the colorimetric method and dual platinum electrode current measurement method for the determination of iodine concentration, developed a highly sensitive method for the determination of sulfur. The sulfur content can be measured from 3 × 10 ~ (-5) M to 1.5 × 10 ~ (-9) M by this method. The average deviation of the measured value does not exceed ± 10%, and the operation is simple and concise, and the result is reproduced Compared with the previous dynamic method, also significantly improved. We studied the effect of solution pH, concentration of each reagent, temperature, zero-valent sulfur and some exogenous ions on the iodine consumption in the reaction. The proposed method was also used to determine the content of negative divalent sulfur in metallic nickel and manganese steel. The sulfur recovery was measured to evaluate the reliability of the method and the results were satisfactory.