a.二氧化碳使蜡烛火焰熄灭。此实验是把无色的密度比空气大的二氧化碳气体,从集气瓶里慢慢倒入立有两支高低不同的燃烧的蜡烛的烧杯中,把空气排出,使两支蜡烛自下而上先后熄灭。倾倒时,需谨慎小心,让二氧化碳沿器壁流下,若操之过急,会使高位烛火先熄灭,或同时熄灭,导致实验达不 a. Carbon dioxide extinguishes the candle flame. In this experiment, a colorless carbon dioxide gas with a density higher than that of air is slowly poured from a gas cylinder into a beaker containing two different burning candles of different heights, and the air is discharged to make two candles bottom-up. Successively extinguished. When dumping, it is necessary to be careful to allow carbon dioxide to flow down the wall. If it is rushed too quickly, the high candle can be extinguished first, or it can be extinguished at the same time, causing the experiment to fail.