Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 °C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 10.7 g of biphenyl in 33.9 g of benzene?

Answer 1

moles biphenyl = grams/molar mass
moles benzene = grams/molar mass
mol fraction benzene = Xbenzene = mol benzene/total moles.

partial pressure benzene = Xbenzene*P_{normal v.p.}

Answer 2

I did what you said and didn't get the correct answer :(

Answer 3

Post your work and I'll try to find your error.

Answer 4

Can someone confirm the answer for this. I worked it out and got an answer of 85.5 torr. Is this right? Can someone please put the answer to this so I can check. Thanks. That would be helpful.

Answer 5

I worked it and obtained 86.9 torr which is close to your number but not quite the same. I used 154 for the molar mass of biphenyl and I used 78 for the molar mass of benzene.
If you will post your work I'll look at it. Please make a new post of it--this one is getting a little far from the front page.