自然界中,有一些固体物质易溶于水,它们的溶解度随温度的升高而增大,随温度的降低而减小。当它们的热饱和溶液冷却后,它们就会以晶体的形式析出。这些晶体,有一定的几何形状,很规则,也很漂亮。学了固体物质的溶解度以后,我了解到明矾就是这样的一种物质。为了得到一个较大的明矾晶体,我做了这样一个家庭小实验。在厨房,我先配制了一杯明矾的热饱和溶液,然后放在室外冷却。第二天,杯底便析出了好多小的明矾 In nature, there are some solid matter soluble in water, their solubility increases with increasing temperature, decreases with decreasing temperature. When their hot saturated solution cools, they precipitate as crystals. These crystals, with certain geometry, are regular and beautiful. After learning the solubility of solid matter, I learned that alum is such a substance. In order to get a larger alum crystal, I did such a small family experiment. In the kitchen, I prepared a cup of hot alum solution and then cooled outdoors. The next day, the cup bottom will precipitate a lot of small alum