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贵刊1987年第3期刊登的“鉴别 Fe~(2+)离子和 Fe~(3+)离子方法14种”一文,有几处不妥的地方,提出一点看法,以便商讨。一、二氧化硫法将 SO_2分别通入含 Fe~(2+)和 Fe~(3+)的溶液中,该文所叙述的现象和反应方程式,是错误的。1.从实验的角度讲,将 SO_2通入含 Fe~(2+)的溶液中并无浅黄色浑浊出现。为此,我又作了专门的验证实验,发现溶液中既无硫沉淀,也无 FeSO_(?)沉淀,(因溶液绝对呈酸性。)溶液也未呈褐黄色。2.从理论上讲,依电极电位(酸性介质):H_2SO_3+4H~++4e(?)S↓+3H_2OE~0=0.45伏Fe~(3+)+e(?)Fe~(2+) E~0=0.770伏显然,E~0H_2SO_3/S E~0Fe~(3+)/Fe~(2(?)),说明在酸性条件下,只能是 Fe~(3+)将 S 氧化为 H_2SO_3,而不
The article “Distinguishing 14 Methods of Fe~(2+) Ions and Fe~(3+) Ions” published in the 3rd issue of 1987 by the Chinese Journal of Indications has several points that are not appropriate, and I would like to make some suggestions for discussion. 1. The sulfur dioxide method passes SO 2 into the solution containing Fe 2+ and Fe 3 , respectively. The phenomena and reaction equations described in this article are wrong. 1. From an experimental point of view, no light yellow turbidity appears in the solution of SO 2 in Fe 2 + . For this reason, I also conducted a special verification experiment and found that neither the sulfur precipitate nor FeSO_(?) precipitated in the solution (because the solution was absolutely acidic). The solution was also not brownish yellow. 2. Theoretically speaking, depending on the electrode potential (acidic medium): H2SO3+4H~++4e(?)S↓+3H_2OE~0=0.45 volt Fe~(3+)+e(?)Fe~(2+) E~0=0.770 volts apparently, E~0H_2SO_3/SE~0Fe~(3+)/Fe~(2(?)), indicating that under acidic conditions, only Fe~(3+) oxidizes S to H_2SO_3, not