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结晶法是分离混合物的一种常用的方法.结晶是从溶液中形成晶体的过程,具体可分为冷却结晶和蒸发结晶.利用结晶的原理,采用冷却结晶和蒸发部分溶剂结晶,可以把可溶性的混合物进行分离,但是,大多数初中学生对此感到很难理解.本文列举两个例题,进行定量解析,以帮助学生理解为何结晶法能分离混合物.表1为 KNO_3和 NaCl 在20℃、60℃时
Crystallization is a commonly used method for separating mixtures. Crystallization is the process of forming crystals from a solution, which can be divided into cooling and evaporating crystals. By using the principle of crystallization, by cooling and evaporating some of the solvent crystals, the soluble However, most junior high school students find it hard to understand.Two examples are given here for quantitative analysis to help students understand why the crystallization method can separate the mixture.Table 1 shows the effect of KNO 3 and NaCl at 20 ℃, 60 ℃ Time