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义务教育课程标准实验教科书九年级《化学》上册第27页有一个“测定空气里氧气含量”的实验,虽然我多次做了该实验。但测定的结果都不尽如人意。经认真思考,我认为该实验有以下缺陷:1.没有考虑导管中水的体积;2.没有考虑压强的作用(当冷却到室温且再没有水进入集气瓶时,只要调整集气瓶导管口和外界量筒液面在同一高度,便会有少量水进入集气瓶);3.瓶内底部的氧气不一定全部耗尽;4.目测进入集气瓶中水的体积和原来空气所占体积的比值不够准确,易造成偏差(例如,3位上讲台的同学目测的结
Compulsory Education Curriculum Standards Experimental Textbook Grade 9 Chemicals Volume 1 Page 27 There is an experiment to determine oxygen content in the air, although I have done this experiment many times. However, the results of the tests were not satisfactory. After careful consideration, I believe that the experiment has the following drawbacks: 1. The volume of water in the catheter is not taken into consideration; 2. The effect of pressure is not considered (when cooled to room temperature and no water enters the gas cylinder, only the gas cylinder tube is adjusted. The mouth and the outside cylinder are at the same height, so there will be a small amount of water entering the cylinder; 3. The oxygen in the bottom of the bottle may not be exhausted; 4. The volume of the water in the cylinder and the air The ratio of the volume is not accurate enough to cause deviations (for example, 3 points on the podium