21. Kinetic Theory of Ideal Gases

Laboratory environments can achieve pressures of 3.5×10^-13 atm and temperatures of 300K. Calculate the mean free path (in km) of air molecules, which you can assume are diatomic.

In the context of the mean free path of gases, which expression best represents the mean free time between collisions, $\tau$, for electrons moving in an aluminum wire, given the mean free path $\lambda$ and the average speed $v$ of the electrons?

Given that the mean free path of a helium atom in helium gas at standard temperature and pressure is $0.2\mu m$, which of the following changes would most likely decrease the mean free path of the helium atoms?