Apologies if it's been asked before, but this came up on another thread. The Kinetic Theory of Gases says that hydrogen molecules at room temperature and pressure are travelling at circa 4000mph. So if I were to suddenly decap a canister of hydrogen in a vacuum chamber, I should see molecules coming out at 4000mph. This seems like an explosive velocity that ought to blast the opposite wall of the chamber in the twinkling of an eye. It doesn't seem to square with my layman's experience. Can any more knowledgeable posters tell me about any experiments that prove the high velocity of the kinetic gas molecules?