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在化学实验中,为准确无误地把实验现象展示给学生,实验器材的选择甚为重要。但有些器材无处可买,所以,收集材料自制教具,对提高课堂教学质量有一定作用。例如碎玻片、破试管在某些实验中就有一定的利用价值。1 加热锌与硫酸反应后的液体 初中化学[实验2—2]中的第二步,加热锌与硫酸反应后的液体,课本中介绍是用蒸发皿进行加热,但在演示时,由于时间的关系,只能加热少量液体,因此,所得到的固态硫酸锌也是很少的(硫酸锌晶体是无色),在白色蒸发
In chemical experiments, the selection of experimental equipment is very important for accurately presenting the experimental phenomenon to students. However, some equipment can’t be bought. Therefore, the collection of materials for self-made teaching aids has a certain effect on improving the quality of classroom teaching. For example, broken slides and broken test tubes have certain value in some experiments. 1 The second step in the process of heating the zinc and sulfuric acid after the reaction of the liquid junior high school chemistry [Experiment 2-2], heating the zinc and sulfuric acid after the reaction, the textbook describes the use of evaporating dish heating, but in the demonstration, due to the time The relationship, can only heat a small amount of liquid, therefore, the resulting solid zinc sulfate is also very little (zinc sulfate crystal is colorless), evaporation on white