[Immortal]

  the question is
"a gas of an unknown molar mass was allowed to effuse through a small openingn under constant-pressure conditions. It required 105 s for 1.0L of teh gase to effuse. Under identical conditions it required 31 s for 1.0L of O2 gas to effuse. Calculate the molar mass of the unknown gas."

i calculated it but i think i did it wrong.. the rate given are in a weird form..
i had the problem setup as follows sqrt Mx ( molar mass unknown/ sqrt 32= 1L/31s/ 1L/105s. the molar mass i found was 4.377 is this correcT?

[Mitch]

How could a gas with a lower MW than oxygen effuse slower than Oxygen? Don't loose your chemical intuition when dealing with these kinds of problems

[Immortal]

yea the concept doesn match my numbers, that why i was wondering how i would do this.. a ta mentioned "The time it takes to effuse (for any given volume of gas) is inversly proportional to u (rms speed)." but i dunno how i would setup the prob.

[Donaldson Tan]

http://www.chemicalforums.com/index.php?board=2;action=display;threadid=2064;start=msg9084#msg9084