So even if the pressure of the balloon and the atmosphere in the helium room are at 1 bar, the helium would continue to migrate in until the partial helium pressure is equalized? Doesn't the total pressure in the balloon, rising above the room pressure, prevent this from actually happening...
So that would mean if I blew a balloon with helium and left it for a period of time, the balloon would start swelling because of the O2 and N2 migrating inwards?
Say I have a small solid polymer container filled with gas A. The walls of the container are semi-permeable, so gas A on inside can't get through/out. On the outside, gas B at atmospheric pressure, which can migrate through the membranes of container. Pressure inside the container is 0,6 bar...