86 Videos: Gases

The Ideal Gas Law: Crash Course Chemistry #12

Gases are everywhere, and this is good news and bad news for chemists. The good news: when they are behaving themselves, it’s extremely easy to describe their behavior theoretically, experimentally and mathematically. The bad news is they almost never behave themselves.

Ideal Gas Problems: Crash Course Chemistry #13

We don’t live in a perfect world, and neither do gases – it would be great if their particles always fulfilled the assumptions of the ideal gas law, and we could use PV=nRT to get the right answer every time. Unfortunately, the ideal gas law (like our culture) has unrealistic expectations when it comes to size and attraction: it assumes that particles do not have size at all and that they never attract each other. So the ideal gas “law” often becomes little more than the ideal gas estimate when it comes to what gases do naturally. But it’s a close enough estimate in enough situations that it’s very valuable to know. In this episode, Hank goes through a bunch of calculations according to the ideal gas law so you can get familiar with it.

Real Gases: Crash Course Chemistry #14

Hank bursts our ideal gas law bubble, er, balloon, and brings us back to reality, explaining how the constants in the gas law aren’t all that constant; how the ideal gas law we’ve spent the past two weeks with has to be corrected for volume because atoms and molecules take up space and for pressure because they’re attracted to each other; that Einstein was behind a lot more of what we know today than most people realize; and how a Dutch scientist named Johannes van der Waals figured out those correction factors in the late 19th century and earned a Nobel Prize for his efforts.

Partial Pressures & Vapor Pressure: Crash Course Chemistry #15

This week we continue to spend quality time with gases, more deeply investigating some principles regarding pressure – including John Dalton’s Law of Partial Pressures, vapor pressure – and demonstrating the method for collecting gas over water.

Passing Gases: Effusion, Diffusion and the Velocity of a Gas: Crash Course Chemistry #16

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.