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?

I know I need to assume that the chamber volume is much greater than the bulb volume and to consider the number of states available to helium and its particle density. I want to say that half of the He will effuse into the bulb and half will stay out, allowing He to occupy the greatest number of states available, but this line of thinking will not work since the chamber volume is much greater than the bulb. Is there a specific equation I can look at/decipher in order to make this a bit more clear?

Hint look up osmosis