In a diffusion pot experiment, carbon dioxide is attracted to a beaker, while helium is unattracted to a beaker. Why is it like that?

Baloo55th

I'm slightly puzzled as to the meaning of the question. When using a porous pot for diffusion, the gases aren't attracted to the beaker as such. When a 'lighter than air' gas like hydrogen is used, the hydrogen molecules will pass through the pot quicker than the 'air' molecules will diffuse outwards, so the pressure in the pot goes up. Carbon dioxide is 'heavier than air', and moves slower, so the pressure in the pot goes down as more air leaves than CO2 goes in. Helium is 'lighter than air', so it will diffuse into the pot more than the air will diffuse out, so the result is similar to that for hydrogen, except that the pressure will not go up quite as much - helium being denser than hydrogen. A good illustration of this is at http://www.practicalphysics.org/go/Experiment_624.html;jsessionid=alZLdQlAHb1 Aug 27 06, 6:29 AM