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一、二氧化碳熄灭蜡烛火焰初中化学第五章第二节二氧化碳的性质用途部分[实验5—3]二氧化碳熄灭蜡烛火焰的实验现象:底下的蜡烛先灭,上面的蜡烛后灭。由此得出结论:1.二氧化碳的密度比空气大。2.在一般情况下,二氧化碳既不能燃烧也不支持燃烧。因此,二氧化碳可以用来灭火。对此学生会质疑,为什么说在一般情况下,二氧化碳不能燃烧也不支持燃烧呢?所有的可燃物着火都可以用二氧化碳熄灭吗?为答此疑,我在教学中补充了一个实验:将镁带先在空气中点燃,然后放入充满二氧化碳的集气瓶中,让学生观察现象,结果镁在二氧化碳中剧烈燃烧,瓶内壁产生大
First, the carbon dioxide extinguishes the candle flame junior high school chemistry The fifth chapter The second part carbon dioxide nature uses the part [experiment 5.3] the carbon dioxide extinguishes the candle flame experimental phenomenon: The bottom candle first extinguishes, above the candle extinguishes. This concludes: 1. Carbon dioxide has a higher density than air. 2. Under normal circumstances, carbon dioxide can neither burn nor support combustion. Therefore, carbon dioxide can be used to extinguish fire. The students will question this question. Why do you say that under normal circumstances, carbon dioxide cannot be burned or burned? Can all of the combustibles catch fire with carbon dioxide? To answer this question, I added an experiment in teaching: First ignite in the air, and then put in a collection cylinder filled with carbon dioxide, so that students observe the phenomenon, as a result of magnesium in the carbon dioxide intense combustion, the bottle wall produces large