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众所周知,空气的成分按体积计算,大约是:氮气78%、氧气21%、稀有气体0.94%、二氧化碳0.03%、其他气体和杂质0.03%。为了证实空气里的氧气所占体积百分数约为21%,现行中学化学教材设计了用燃烧红磷来测定消耗氧气体积的实验。实验的结论是集气瓶里水面上升,流入水的体积大约为原来空气体积的1/5。但是,这个实验为什么要采用红磷来燃烧,其他可燃物可以代替吗?为什么要用水,其他液体能代替吗?流入水的体积真的大约为原来空气体积的1/5吗?为什么?
It is well-known that the composition of air is approximately 78% of nitrogen, 21% of oxygen, 0.94% of rare gas, 0.03% of carbon dioxide and 0.03% of other gases and impurities by volume. In order to confirm that the volume of oxygen in the air accounts for about 21% of the volume, the current middle school chemistry textbook was designed to measure the oxygen consumption by burning red phosphorus. The conclusion of the experiment is that the water level in the gas tank rises, and the volume of inflow water is about 1/5 of the original air volume. However, why should this experiment be red phosphorus to burn, other combustibles can be replaced? Why water, other liquids can be replaced? The volume of water into the really about the original air volume of 1/5 and why?