制备澄清的石灰水在生物学实验中主要用以检验CO2气体。制备的方法很简单,即取一些Ca(OH)2兑入足够的水,静置数个小时或一昼夜,然后取其上清液即可。但是取上清液时,会发现上清液的表面常常浮着一层很薄的灰白色物质,这是由于液体表层的Ca(OH)2与空气中的CO2发生反应从而产生微 Preparation of clear lime water is mainly used to test CO2 gas in biological experiments. The method of preparation is very simple, that is, taking some Ca(OH)2 into enough water, standing for several hours or day and night, and then taking the supernatant. However, when the supernatant is used, it is often found that the surface of the supernatant is often covered with a thin layer of grayish white matter. This is due to the reaction of Ca(OH)2 in the surface layer of the liquid with CO2 in the air to produce microscopic particles.