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初中阶段根据溶解度概念计算的习题中有这样一种类型:将一定温度下的某物质的饱和溶液改变条件(改变温度,或改变溶剂的含量,或者两者均改变),计算饱和溶液中溶质的含量变化(一种是析出一定量的溶质,一种是需要补充一定量的溶质达到饱和)。这类习题的解决,必须从溶解度的概念出发,从溶液的含量的变化着手(分析原题)。找出对应的比例关系。由于审题时所找出的对应关系有多种情形,故这类习题有多种解法。初中学生对此往往不能适应。本人就这类习题采取了画变化过程示意图的教法使学生易于从直观的图形上自我分析、总结、列出比例式,效果较好。现举例如下:
In the junior high school stage, the problem solved according to the concept of solubility is that of changing the condition of a saturated solution of a substance at a certain temperature (changing the temperature, changing the content of the solvent, or both) and calculating the amount of solute Content changes (one is precipitation of a certain amount of solute, one is the need to add a certain amount of solute to saturation). The solution to these problems must proceed from the concept of solubility and proceed with changes in the content of the solution (analysis of the original title). Find the corresponding proportion of relations. There are many kinds of situations for the corresponding relations found during the trial examinations, so there are many solutions to this type of exercises. Junior high school students often can not adapt to this. I have taken this type of exercises to draw a diagram of the process of changing the process of teaching students to easily from the intuitive graphical self-analysis, sum up, listing the proportion, the better. Here is an example: