摩尔分数或比率，但它是有单位的。
那么B在气相中的摩尔分数是多少？
让我们代入，这个表中的摩尔分数。
So let's plug in what these mole fractions are from our table here.
好，这是二点温度下的液态摩尔分数。
这是告诉我们,液相摩尔分数的曲线。
So this is the one that's showing us the mole fraction in the liquid phase.
好，让我们看看温度,和摩尔分数相图。
OK, so we're going to look at temperature and mole fraction phase diagrams.
这是气体中a的摩尔分数。
也就是，摩尔分数不再是，压强的函数。
Namely, instead of showing the mole fractions as a function of the pressure.
教授：不，因为这是气态中的摩尔分数。
PROFESSOR: No. Because, so it's the mole fraction in the gas phase.
这是yB，气相摩尔分数。
所以在气相中，我们有摩尔分数yA和。
其中有一些摩尔分数的。
考虑A和，在液态以一定的摩尔分数混合。
B We're going to have a molar fraction in the liquid phase for a and B.
你会和之前开始的时候，有不同的摩尔分数。
And you'll have some different mole fraction than you started with before.
这是液相的摩尔分数。
这就是B的摩尔分数。
在气体中是yA和，这是气体中的摩尔分数。
yB And yA and yB in the gas phase, the mole fractions in the gas phase.
直接读出来，可得是xB，是液相摩尔分数。
So that means just reading off it, this is xB, that's the liquid mole fraction.
当然，在极限处，两个摩尔分数分别是零和一。
Of course, at the limits they're still, both mole fractions they're zero and one.
这分压等于气相中b的摩尔分数，乘以总压强。
It's the molar fraction of B in the gas phase times the total pressure.
如果我们到达那，它告诉了我们气相的摩尔分数。
And if we go over here, this is telling us about the mole fraction in the gas phase.
溶质的蒸汽压，和溶液中溶质的摩尔分数成正比。
That the vapor pressure of the solute is related to the mole fraction in the solution.
气体摩尔分数。
更不易挥发的物质，在气相中的，摩尔分数减小了。
You decrease the mole fraction of the less volatile material in the gas phase.
摩尔分数很小。
对每一个组分我们都要知道，它在各个相中的摩尔分数。
And for each component we have to describe its mole fraction in that particular phase.
现在，当然，由于这是摩尔分数，它总是处于零到一之间。
Now, of course, since this is a mole fraction, it's always between zero and one.
如果你看，好，现在我们也可以确定，气相中的摩尔分数。
If you look and see, well, now we should be able to determine the mole fraction in the gas as well.
我们援引了摩尔分数的道尔顿定律，要服从质量守恒定律。
We invoke Dalton's Law of molar proportions, we write it subject to conservation of mass.
或者说如果你知道A的摩尔分数，和温度，你就知道了压强。
Or if you know just the molar fraction of a, and the temperature, then you know the pressure above.
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