众所周知,如果把食盐放在潮湿的地方,它就会吸收水蒸汽而变粘。如图1所示,若把干的食盐放入一个容器里,而把水灌进另一个容器里,然后把这两个容器用管子连接起来,构成一个封闭的小系统。通常,这个小系统是不会有什么变化的,但如果将其中的空气抽出使之变成真空,则水就会蒸发,而食盐吸收水蒸汽,能使容器保持低压状态,水就会不断蒸发。 It is well known that if salt is placed in a damp place, it absorbs water vapor and becomes sticky. If, as shown in Figure 1, the dried salt is placed in a container and water is poured into another container, the two containers are then pipe-connected to form a closed system. Normally, this small system will not change anything, but if the air is drawn out to make it a vacuum, the water evaporates and the salt absorbs the water vapor and keeps the container under low pressure, and the water evaporates .