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一、借助幻灯投影提高演示实验的可见度和真实感 在化学教学过程中,利用幻灯投影可以变抽象为直观,加深学生对知识的感性认识。如讲原子-分子论知识,微观粒子运动是学生难以理解的,为了帮助学生理解,我设计了下面的幻灯投影。(1)将盛有无色酚酞试液的表面皿与盛有滴入酚酞试液呈浅红色的浓氨水的表面皿分别置于幻灯机上投影,无现象发生。然后将两表面皿放在一起,用玻璃罩盖住,再投影,可看到无色酚酞试液逐渐变红,这表明氨分子从一个器皿跑到另一器皿去了,从而形象、生动地说明了分子的存在。(2)将盛有浓盐酸的表面皿与前两个表
1. Enhancing the Visibility and Reality of Demonstration Experiments with Slide Projection In the course of chemistry teaching, the use of slide projections can be abstracted as intuitive, deepening students’ perceptual knowledge of knowledge. Such as atom-molecular knowledge, microscopic particle movement is difficult for students to understand, in order to help students understand, I designed the following slide projection. (1) A watch glass containing a colorless phenolphthalein test solution and a watch glass containing phenolphthalein test solution, which was light red concentrated ammonia, were placed on a slide projector and no phenomenon occurred. Then put the two watch glass together, covered with a glass cover, and then projected, it can be seen that the colorless phenolphthalein test solution gradually turns red, indicating that the ammonia molecules went from one vessel to another, and thus vividly and vividly. Explains the existence of a molecule. (2) The watch glass containing concentrated hydrochloric acid and the first two tables