[问题讨论]盐水变淡了，还是变咸了？ [复制链接]

感觉有陷阱呢！！
李老师，说说你的高见

个人觉得变浓了。（上午打算发的时候，不知道怎么回事，网段了）
先假设这两种溶液都符合拉乌尔定律，P=P*ΧC   ,（把水想象成无限无限稀的Nacl溶液）这样Nacl溶液表面的蒸汽压必定小于水上空的蒸汽压，这样微观上Nacl溶液会出现蒸发现象。

应该是不变吧

肯定是变淡了，

By theory, the cup on the left "water" 变浓了, the one on the right "盐水"变淡. if left 静置, giving a billion years or so, both will have the same salinity. Left alone for trillion years or so, both cups and the 容器 will become one.

In real world, the only changes are billions & billions electrons  exchanged between containers but can't be measured by human and hundreds & hundreds seconds wasted for this kind of question

If you don't think so, do the experiment and you will get the answer.

BTW, I recommend Prof to make posts to motivate young professional to solve real world problems. Like how to stop worrying material gain and have a positive attitude.

世上本无事，庸人自扰之

引用第24楼ytlee于2009-12-02 21:53发表的  :
By theory, the cup on the left "water" 变浓了, the one on the right "盐水"变淡. if left 静置, giving a billion years or so, both will have the same salinity. Left alone for trillion years or so, both cups and the 容器 will become one.
In real world, the only changes are billions & billions electrons  exchanged between containers but can't be measured by human and hundreds & hundreds seconds wasted for this kind of question
If you don't think so, do the experiment and you will get the answer.
.......

这个有点夸张啊，都到分子运动上去了，在人类有限的历史内，要想两边盐度一样，那是不可能的；有那时间估计边容器材质都要通过分子扩散成虚无了，呵呵。开始时，两边都蒸发，盐的浓度变大；但是如楼上网友指出的，根据拉乌尔定律（注：蒸汽压低应该是不容易挥发的），
与水相比，盐水的蒸汽压低点，所以长时间后，密闭容器内的压力应该接近于水的饱和蒸汽压，这时盐水上方的压力大于盐水的蒸汽压，水蒸汽要凝结，右边的盐水变淡。只要增加点温度，加快蒸发速度，在实验条件下应该是可以检验这个结果的。

个人觉得变淡了，嘿嘿。看看各位的高见。

密闭容器，挥发是次要的，认为密闭容器外的温度压力等环境条件改变可能得到不同的结论

到底有没有正确答案啊！！