So this is a fairly simple conceptual question: can you estimate/compare the mean free paths for individual components of a mixture of gases? I'm primarily looking at the equation given here and the information accompanying it. Consider the case where we have several individual, separate pure samples of different gases, all at the same pressure and temperature and containing the same number of moles. We can estimate the relative values of their mean free paths by comparing their molecular sizes. In this situation it's easy to recognize that the gas particles in a sample of CO2 will have a shorter mean free path than those in a sample of helium. However, if we mix the gases together, can we still make such a comparison when they're now interacting with particles of different size and velocity? I ask because the equation derived at HyperPhysics (linked above) appears to be based on the Maxwell speed distribution, which I'm not sure is valid for a mixture of gases. So if I have a chamber containing one mole each of several gases in a mixture, can I still compare the gases' individual mean free paths and conclude that, even in a mixture, CO2 would have a shorter mean free path than He? I apologize if this is obvious or something, I'm a bit out of my league trying to examine the math and concepts involved in determining mean free path. Thanks for any replies!