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甲苯的化学性质比苯活泼,能被高锰酸钾氧化,使高锰酸钾溶液褪色。因此常常利用这一性质和现象来鉴别苯和苯的同系物。但在课堂演示实验和学生实验时,往往出现甲苯不能使高锰酸钾溶液褪色或者苯也能使高锰酸钾褪色的“异常”现象。计对这一情况,我们进行了认真的分析,多次实验,并进行了如下改进。 1 适当的加热 由于甲苯不易溶于水,当甲苯与高锰酸钾溶液混合时,很快分成两层,即甲苯层和水层,不能使高锰酸钾与甲苯充分接触,很难发生反
The chemical nature of toluene is more active than that of benzene and can be oxidized by potassium permanganate, causing the potassium permanganate solution to fade. Therefore, this property and phenomenon are often used to identify homologues of benzene and benzene. However, in classroom demonstration experiments and student experiments, there are often “abnormal” phenomena in which toluene cannot fade the potassium permanganate solution or benzene can also cause potassium permanganate to fade. In this case, we conducted a careful analysis, repeated experiments, and made the following improvements. 1 Proper heating Because toluene is not easily soluble in water, when toluene is mixed with potassium permanganate solution, it is quickly divided into two layers, ie, a toluene layer and an aqueous layer, which cannot fully contact potassium permanganate with toluene, and it is difficult to reverse it.