论文部分内容阅读
《中学化学教学参考》2013年第5期李林梅老师的“弹响教学的美丽音符一两则九年级化学课堂演示实验的改进”一文中,在演示固体NaOH溶于水放热这一性质时,对实验进行改进,改为取一只试管,加入1/3体积的水,并加热至沸腾,离开火源后在停止沸腾的水中加入固体NaOH,固体NaOH全部溶解,水很快重新沸腾。利用此反应说明固体NaOH溶于水放热而使溶液沸腾。下文就通过一些实验事实,说明这种改进的不合理之处。
“High School Chemistry Teaching Reference” 2013 the fifth Li Linmei teacher “syllables teaching a beautiful note one or two ninth grade chemistry classroom demonstration experiment ” in a paper, the solid NaOH dissolved in water to show the nature of the heat , To improve the experiment, instead of taking a test tube, add 1/3 volume of water and heated to boiling, after leaving the source of fire in the stop boiling water added solid NaOH, solid NaOH all dissolved, the water quickly re-boil . Use this reaction shows solid NaOH dissolved in water to heat and boil the solution. In the following, some experimental facts are used to illustrate the unreasonableness of such improvements.