Chemistry Question

[bleeb]

You have two miscible liquids A and B distilled at 760 mmHg. At start, mole fraction of A is 90.0 and B is 10.0. At the end, the condensed vapor is mole fraction A is 15.0 and B is 85.0

what are the partial pressures of A and B?
what are the vapor pressures of pure A and B?

 

[bleeb]

Is no one smart enough to handle this challenge?

 

[firewall]

I had chemistry in my last semester. I have forgotten it by now.

Why not search and read up on partial pressure?

 

[JDrake]

Originally posted by: bleeb
Is no one smart enough to handle this challenge?

Chemistry is next year 🙁

 

[bleeb]

Originally posted by: asadasif
I had chemistry in my last semester. I have forgotten it by now.

Why not search and read up on partial pressure?

I have an answer, I just don't know if it's right because one of the pressures is huge.

 

[hypn0tik]

PV = nRT

 

[Googer]

This subject belongs in the Highly Technical Secton of forums.anandtech.com

http://forums.anandtech.com/categories.aspx?catid=50&flcache=1995409&entercat=y

 

[Cawchy87]

Originally posted by: Googer
This subject belongs in the Highly Technical Secton of forums.anandtech.com

http://forums.anandtech.com/categories.aspx?catid=50&flcache=1995409&entercat=y

? I remember doing this in grade 12

 

[bleeb]

still no one??

 

[StrangerGuy]

Something to do with relative volatility?

 

[da loser]

here's a guess, haven't done this stuff in a long time

dalton's law
P=EPi, where Pi is equal toP=mi all in the gas phase
there Pa=760*.15 Pb =760*.85 Pa=114 Pb=646

raoult's law combined with dalton's
P=E(Pv*X)=EPi=> Pva*Xa=Pva*.9=Pa= 760*.15 => Pva=126.6 Pvb=6460

which if you think about seems right. B is a very small fraction of the liquid, yet it becomes a very large fraction of the gas, since the total pressure will be a function of the liquid fraction, then it must have a very large vapor pressure.