# Rate of diffusion/effusion and concentration?

#### Lostintime

I was wondering how concentration affected the rates of diffusion and effusion.

I heard concentration does not affect effusion
But increasing conc SLOWED diffusion because It reduced the mean free path of the particles.

Is this correct?

#### chiddler

5+ Year Member
I want to point out that the Vrms = sqrt(3RT/m) can only help us determine ratio of diffusion rate of two gases. So that won't help us with your question.

Rate of diffusion is rate of gas flow through a given area. Intuitively, it is highest when concentration difference is high just like osmosis or diffusion.

#### hellocubed

Vrms = sqrt(3RT/m)
Don't forget that this only considers velocity, mass, and time.

It has nothing to do with mean free path.
Remember the difference between mean free path, and root mean square speed.

Mean free path is inversely proportional to concentration. So it's kind of strange that concentration boost rate, and its decreasing mean free path deters it.
I suppose concentration wins the tug of war...

#### UrshumMurshum

If you had one particle in a box with a hole in it, the rate of diffusion would be pretty low.

If you had 10^23 particles in a box, the rate of diffusion would be comparatively higher.

#### ipodtouch

10+ Year Member
However, if you had one Particle, The diffusion would become complete much much faster due to infinite mean free path.

Thats the thing.

If you have a motorcycle, you could travel much faster than an aircraft carrier. However you will be carrying less particles.

Its a difference of symantics.

Having the "rate" and the "speed"

#### ipodtouch

10+ Year Member
Also, you are confusing diffusion and effusion.

Diffusion does not involve "holes"

It is the movement of fluid through free space