Posted by Capacino on .
Effusion/Diffusion Chemistry Help!!!
If 4.83mL of an unknown gas effuses through a hole in a plate in the same time it takes 9.23mL of Argon, Ar, to effuse through the same hole under the same conditions, what is the molecular mass of the unknown gas? (146amu)
Responses:
* chemistry  DrBob222, Wednesday, June 17, 2009 at 10:19pm
Isn't this just standard use of
rate1/rate2 = sqrt(M2/M1)?
I get 146 also.
I am trying to do this again and cannot figure out what I am doing wrong??
4.83/9.23=.524 when I square that I get .723 not 146.
Any suggestion?

chemistry 
DrBob222,
You are squaring incorrectly. Try multiplying 0.524 x 0.524 and I get something like 0.28 or so. You need to do it exactly (and I would divide 4.83/9.23 to get a number and square it without taking it out of the calculator. That way, all of the digits remain in the calculator. Doing that I get 0.27384.)

chemistry 
Juggernaut,
Thank You, you are absolutely correct!