An ideal solution is formed by mixing liquids A and B at 298K. The vapour pressure of pure A is 180 Torr and that of pure B is 82.1 Torr. Assume that there are only A and B molecules in the vapour phase.
If the mole fraction of A in the vapour is 0.450, what is the mole fraction of A in the solution?
- much appreciated any help ne1 can give, iv been tearing my hair out and am now bald becos of this question :(
2007-12-09 00:21:27 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
No wonder you're exasperated. I love and teach chemistry, and hate this kind of question which is designed to make simple things look as difficult as possible.
Partial pressure of A = 180 x Y (Y is mol fraction A)
Partial pressure of B = 82.1 x (1 - Y) (since whatever is not A is |B)
Mole fraction of B in vapour = 0.550 (similar reasoning)
so (180 x Y)/[82.1 x (1 - Y)] = 0.450/0.550
And all you are left with is a little bit of messy algebra, which I leave to you.
2007-12-09 01:43:51 · answer #1 · answered by Facts Matter 7 · 0⤊ 0⤋