Why Don't Gas Mixtures Segregate in a Sealed Container?

[mviswanathan]

As I understand, a gas mixture, say 50% C4H10 and 50% Air, will not segregate and form layers with the heavier gas at the bottom even in a sealed container. This is due to the constant movement of gas molecules.

Is my understanding correct?

Does this depend on pressure?

Thanks

 

[mgb_phys]

Correct
One way to separate it is to 'increase gravity', by spinning the gas in a centrifuge you can force the heavier gas to the outside and separate them.

 

[mviswanathan]

So, does it mean that the gravity can separate the mixture components in layers?

Well, the context is like this:
We are trying to use Butane + Air mixture in place of Natural Gas in a burner and fire the mixture with additional air. That looks ok.
But worried that when we put of the system with the stagnat gas mixture in the piping, the elements could segragate and form layers with the Butane at the bottom. Going by the theory that, the pressure of the gas on the walls of the container is due to continuous bombardment of the gas molecules, there will be continuous mixing of the mixure components and the segregation will not take place.
May be the segregation could occur at very low absolute pressures? Then, how low pressure?
Is the worry justified at near atmospheric pressure range?

 

[mviswanathan]

I got answer to my query in the following article:

http://www.infoplease.com/ce6/sci/A0815496.html


Thanks

 

[PJC01]

Your understanding is correct. In a mixed gas, the molecules are constantly moving and colliding with each other, which prevents any sort of segregation or layering. This is known as Brownian motion and is a fundamental principle in gas behavior.

The behavior of a gas mixture does not depend on pressure. As long as the container is sealed and the temperature remains constant, the gas molecules will continue to move and mix evenly throughout the container. However, changes in temperature and pressure can affect the overall behavior of the gas mixture, such as changes in volume or density.