Statistical thermodynamics- ideal gases mixture (Reif 3.6)

[sergiopinilla]

A glass bulb contains air at room temperature and at a pressure of 1 atmosphere. It is
placed in a chamber filled with helium gas at 1 atmosphere and at a room temperature. A
few months later, the experimenter happens to read in a journal article that the particular
glass of which the bulb is made is quite permeable to helium, although not to any other
gases. Assuming that equilibrium has been attained by this time, what gas pressure will the
experimenter measure inside the bulb when he goes back to check? Please help, the solutions manual says its 2 atmospheres but I don't really know how to start.

 

[Andrew Mason]

A glass bulb contains air at room temperature and at a pressure of 1 atmosphere. It is
placed in a chamber filled with helium gas at 1 atmosphere and at a room temperature. A
few months later, the experimenter happens to read in a journal article that the particular
glass of which the bulb is made is quite permeable to helium, although not to any other
gases. Assuming that equilibrium has been attained by this time, what gas pressure will the
experimenter measure inside the bulb when he goes back to check? Please help, the solutions manual says its 2 atmospheres but I don't really know how to start.

You have to assume that the volume of helium is much, much greater than the volume of the bulb. With a membrane permeable to only helium, what is the relationship between the partial pressure of helium inside the bulb to the helium pressure outside the bulb (ie in the helium chamber surrounding the glass bulb)?

AM