# Change of vapour pressure

1. Nov 20, 2008

### tirrel

Hi... I found this site a lot time ago and sometimes I feel like viewing your problems, maybe in a future I'll be active.... I want to say that this IS NOT an homework, but it's an exercise I was never able to solve and so I try to put it here, even if I don't know whether it is the right section of the forum....

1. The problem statement, all variables and given/known data

I'll try to describe a picture.

This is the situation. Imagine a thorus half-filled with a liquid. At the beginning of course the water will fill the lower part of the torus (part A) and the other part (part B) will be filled with its vapour. Now dived part B using a membrane pouros with respect to the vapour. This membrane at this moment doesn't have physical effects, but it divides part B of the thorus into part B1 and B2.

Now we take a gas which the membrane doen't let pass and pump it at pressure P into part B1 of the thorus.

Data: density of the liquid: $n_L$, density of the vapour $n_v$.

Question: how much has changed the vapour pressure from its initial value?

2. Relevant equations

boh...law of perfect gases?, chemical potentials?, work done by the gas pumped?....

3. The attempt at a solution

Actually I don't have serious attempts to propose... it's years that I haven't got a solution to this problem...