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用瓷坩埚做硝酸钾在熔化状态时的导电性试验,是全日制十年制学校初中课本《化学》中的一个演示实验。这个实验的主要困难是硝酸钾熔化得慢,用酒精灯加热更慢。在瓷坩埚里硝酸钾即使熔化,学生也看不到熔化现象。我们改用自制U形硬质玻管来作硝酸钾加热熔化的容器,因为玻管容积小,硝酸钾用量少,就容易熔化。而且玻管是透明的,容易看到熔化现象。现在把这个实验的方法介绍如下。
Conductivity tests using pottery enamel as the potassium nitrate in the molten state is a demonstration experiment in a full-time 10-year school junior school textbook “Chemistry”. The main difficulty of this experiment is that potassium nitrate melts slowly and is heated more slowly with an alcohol lamp. Even if potassium nitrate is melted in the porcelain bowl, students will not see melting. We used self-made U-shaped rigid glass tubes as containers for the heating and melting of potassium nitrate. Because the glass tube has a small volume and a small amount of potassium nitrate is used, it is easily melted. And the glass tube is transparent, easy to see the melting phenomenon. Now we introduce the method of this experiment as follows.