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初中物理第二册82页“液化”这节课的演示实验,课本上是采用让“水蒸气”喷到一个冷的物体上,然后看到有水滴掉下来以说明气体液化的。但我认为此实验不太妥当,因不能很好地说明变化的本质,我们看到的是还没有喷到冷物体上的“白气”,实际上不是气体,而是已经由水蒸气液化了的微小水滴,所以呈雾状。这样,实际上是水蒸气从玻璃管口喷出后就开始了液化,从而形成了白雾,用冷物体接收,只不过是集小成大,但不能说明水蒸气是
The demonstration experiment of “Liquify” in the junior high school physics booklet, page 82, used textbooks to spray “steam” onto a cold object, and then saw water droplets fall off to explain the gas liquefaction. But I don’t think this experiment is appropriate. Because we can’t explain the nature of the change well, we can see that the “white gas” that has not yet been sprayed on a cold object is actually not a gas but has been liquefied by water vapor. The tiny droplets of water are so misty. In this way, water vapor is actually liquefied after it is sprayed from the opening of the glass nozzle, resulting in the formation of a white mist. Receiving with a cold object is only a matter of small size, but it cannot be explained that the water vapor is