结晶法是高中必须掌握的物质分离提纯的方法之一,是工业流程题目中的重要考点,也是学生理解的难点,如何使用结晶法进行分离和提纯物质,以下举例阐述。一、单一溶质的溶液欲结晶得到溶质晶体,常因物质本身性质的差异而采用不同的结晶办法1.如果溶液在蒸发结晶时,溶质不发生变质则直接采用蒸发结晶的方式得到溶质晶体,如NaCl、K_2SO_4、MgSO_4、Na_2CO_3等,需要指出的是:如果溶质的溶解度随温度变化非常明显,如图1所示,也可采用蒸发浓缩、冷却结晶来获得其晶体, The crystallization method is one of the methods for separating and purifying substances in high school. It is an important test point in the topic of industrial processes. It is also a difficult point for students to understand. How to use crystallization to separate and purify substances is exemplified below. First, a single solute solution to crystallize to obtain solute crystals, often due to differences in the nature of the material and the use of different methods of crystallization 1. If the solution in the evaporation crystallization, solute does not degenerate the direct use of evaporation crystallization obtained solute crystals, such as NaCl, K_2SO_4, MgSO_4, Na_2CO_3, etc. It should be pointed out that if the solute solubility changes with temperature is very obvious, as shown in Figure 1, you can also use evaporation concentration, cooling crystallization to obtain the crystal,