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传统教材上Fe3+转化成Fe2+的实验操作是向2mL1mol／L的FeCl3溶液中滴加3滴稀盐 酸,再加入少量还原性铁粉,观察溶液颜色的变化。这种做法有两点缺陷:一是加少量 铁粉无法保证Fe3+完全转化成Fe2+;二是该反应在常温下进行较慢,要观察到明显的现 象需较长的时间。为此,笔者做了如下改进: 1.向4mL1mol／L的FeCl3溶液中加入5滴稀盐酸,再加入1／4角匙(稍过量)的还原性 铁粉;
The experimental procedure for transforming Fe3+ into Fe2+ in traditional textbooks is to add 3 drops of diluted hydrochloric acid to 2 mL of 1 mol/L FeCl3 solution, and then add a small amount of reducing iron powder to observe the color change of the solution. This practice has two defects: First, the addition of a small amount of iron powder does not guarantee the complete conversion of Fe3+ to Fe2+; second, the reaction proceeds slowly at room temperature, and it takes a long time to observe the obvious phenomenon. To this end, the author made the following improvements: 1. Add 5 drops of dilute hydrochloric acid to 4mL of 1mol/L FeCl3 solution, and then add 1/4 angle spoon (a slight excess) of reducing iron powder;