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空气中氧气含量测定实验是人教版九年级化学教科书上册第27页的实验,笔者结合自己的教学实际,对教科书上的实验进行了改进,现将改进后的实验与大家一起分享。一、实验改进原因教科书上所设计的实验是利用红磷在一定量的空气中燃烧,消耗其中的氧气,再测出剩余气体的体积,从而得出这一定量空气中的氧气含量。纵观整个教材,该实验存在以下不足:一是用笔粗略记号均分,这样做误差较大;二是红磷在瓶外加热时,有白烟生
The determination of oxygen content in the air is an experiment on page 27 of the first edition of the 9th grade chemistry textbook of the People’s Education Press. The author has combined his own teaching practice to improve the experiments on textbooks and now share the improved experiments with everyone. First, the reason for the experimental improvement The experiment designed in the textbook is to use red phosphorus to burn in a certain amount of air, consume the oxygen, and then measure the volume of the remaining gas to obtain the oxygen content of this quantitative air. Throughout the entire teaching material, the experiment has the following deficiencies: First, the pen marks are used to evenly divide the points. This makes the error larger. Second, when the red phosphorus is heated outside the bottle, there is white smoke.