Overview: We have learned over the past few weeks that gases have real-life constraints on how they move here in the non-ideal world. As with most things in chemistry (and also in life) how a gas moves is more complex than it at first appears. In this episode, Hank describes what it means when we talk about the velocity of a gas - to understand gas velocity, we have to know what factors effect it, and how. Hank also teaches you about effusion, diffusion and concentration gradients, before showing off a cool experiment that physically demonstrates the things you have just learned. Sound exciting enough for you? Let's get started.