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溶解度的计算,是初中化学教材的重点,必须使学生牢固地掌握。 从教材看,有关溶解度计算的范例和习题类型大致分为两个方面:(1)溶解度同溶质、溶剂和饱和溶液之间的互算;(2)当温度改变,或温度和溶剂的量都改变时,有关溶质的量的计算。 在教学实践中,我利用“溶液=溶质+溶剂”这一关系式进行溶解度计算,并指导学生作业,收到较好的效果。 例1 把50克20℃的饱和硝酸钾溶液蒸干,得到12克硝酸钾,求硝酸钾在20℃的溶解度。
The calculation of solubility is the focus of junior high school chemistry textbooks and students must be firmly mastered. From the teaching materials, examples of solubility calculations and types of exercises can be broadly divided into two aspects: (1) solubility between solute, solvent and saturated solution; (2) when temperature changes, or both temperature and amount of solvent When changing, calculate the amount of solute. In teaching practice, I use the relationship of “Solution = Solute + Solvent” to calculate the solubility, and guide the students to work and receive good results. Example 1 50 g of saturated potassium nitrate solution at 20C was evaporated to dryness to obtain 12 g of potassium nitrate, and the solubility of potassium nitrate at 20C was determined.