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 seems at first. 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 affect 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. Special Thanks to Matt Young at the University of Montana (Geosciences Department, Environmental Biogeochemistry Lab) who helped with the chemical demonstrations. Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: https://apple.co/3d4eyZo Download it here for Android Devices: https://bit.ly/2SrDulJ Table of Contents Net Velocity vs. Average Velocity 1:17 Effusion 4:47 Graham's Law 5:52 Diffusion 7:22 Concentration Gradients 7:08 Precipitation Reaction with Gases 8:21 Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Instagram - https://www.instagram.com/thecrashcourse/ CC Kids: null