00:03
There, in this question, we are trying to calculate the mole fraction of this mixture of two gases.
00:10
And the way that we calculate mole fraction is by taking the moles of the component we're interested in.
00:16
So in that case, we are interested in the oxygen in this question.
00:20
So we need to take the moles of the oxygen and divide by the total moles in the solution.
00:41
Okay, so therefore, to answer this, we need moles.
00:44
And right now we have percent composition by mass.
00:48
So that percent composition is true regardless what size sample we have.
00:54
And it tells us that it's 37 % oxygen for any size sample and 63 % nitrogen.
01:05
So to keep my math simple, what i'm going to do is assume that i'm working with a 100 gram sample.
01:19
I could use any size sample i want and i'm still going to get the same answer because the percent composition will have that same percent composition regardless the size sample and the mole fraction will not change.
01:33
So i can work with any size sample i want and still get the correct answer...