水在常温和常压下为液态,而加热后开始汽化,我们利用这一极普通的性质,做出一组有关大气的实验。一、证明空气有重量的实验取一容量为1000ml的圆底大烧瓶,装水少许,在酒精灯上加热,达沸腾后持续几分钟,让水蒸汽充分占据瓶中的空间,尽量排尽烧瓶中的空气,然后迅速用橡皮塞塞紧瓶口,不使其漏气(见图1),并同时停止加热,使其自然冷却。在塞住瓶口瞬间,瓶内外的压强相同,随着温度的降低,烧瓶中的水蒸汽又转为液态,烧瓶中留有极少的气体(此时瓶内压强远小于瓶外的大气压强。后面的几个实验都要用到此性质,以下不再复述),待 Water is liquid at normal temperature and pressure, and begins to vaporize when heated. We use this very ordinary property to make a series of experiments on the atmosphere. First, to prove the weight of the air experiment Take a capacity of 1000ml round bottom flask, a little water, heated on the alcohol lamp, boiling for a few minutes, so that water vapor fully occupy the space in the bottle, try to drain the flask In the air, and then quickly plug the bottle with a rubber stopper, not to leak (see Figure 1), and at the same time stop heating, allowing it to cool naturally. Plug in the bottle instantly, the same pressure inside and outside the bottle, as the temperature decreases, the water vapor in the flask and turned into liquid, leaving little gas in the flask (at this time the pressure inside the bottle is much smaller than the atmospheric pressure outside the bottle Behind a few experiments have to use this property, the following will not repeat), to be