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初中化学“分子”一节内容,是学生学习物质结构知识的开始。为了使学生确认分子的真实存在,了解分子的特征:分子之间有一定的距离,分子在不停地运动,分子的质量很小,我作了以下教学尝试。在指导学生阅读课本上有关分子的概念后,再补充两个演示实验和一道计算题: [实验一] 分别用50ml的量筒量取50ml水和50ml酒精,都倒入同一个100ml的量筒中,发现混和后的液体体积小于100ml。这是为什么? [实验二] 把装满水的U形管两端,分别倒插入两只盛水的烧杯中,向其中的一只烧杯中注入高锰酸
The “Chemistry” section of junior high school chemistry is the beginning of a student's knowledge of material structure. In order to enable students to confirm the true existence of molecules, to understand the characteristics of molecules: there is a certain distance between molecules, molecules are constantly moving, the quality of molecules is very small, I made the following teaching attempt. After guiding students to read the textbook on the concept of molecules, and then add two demonstration experiments and a calculation: [Experiment] were used to measure the amount of 50ml cylinder 50ml of water and 50ml of alcohol, are poured into the same 100ml cylinder, The liquid volume after mixing was found to be less than 100 ml. This is why? [Experiment 2] The U-shaped tube filled with water at both ends, respectively, into two water-filled beaker, to one of the beaker of permanganate