mass times moles (NA) equals Molar Mass (MM), substituting MM and solving for u gives
using this last equation we can solve for an individual gas particle's speed rms = root mean square, which is the average square root of the speed of the individual particles.
Use R = 8.3148 , in order for the units to come out in m/s
effusion - the flow of gas particles through a small opening or pinhole in a container.
diffusion - random motion of gas particles.
if the two gases are at the same temperature then:
Experimentally usually measure the time for effusion to occur, this time is an inverse of the effusion rate (lower times-faster effusion rates)
this equation was used for the separation of U238 during WWII by effusion principles.
Deviate at least slightly from Ideal Gas Law because of two factors:
gas molecules attract one another
gas molecules occupy a finite volume
Both of these factors are neglected in the Ideal Gas law. Both increase in importance when molecules are close together (high P, low T)
van der Walls equation
corrects for the attraction between molecules.
nb corrects for the volume of gas molecules
van der Walls constants are given on page 217
(a and b) for above equation.