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 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!

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

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[crashcourse]

Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App! 

[NeonsStyleHD]

Remember kids, v = velocity, V = Volume, m = mass, and M = Molar Mass and you can find the Molar Mass of any atom on the periodic table. :)

[kelansparks]

Thanks again Hank, your the only reason I'm getting through my high school chemistry with a 95%

[mimikinsz]

PLEASE TEACH AT THE UNIVERSITY OF FLORIDA. We need you so much! Im passing but Id much rather pay to be taught not pay to teach myself! 

[CreightonMiller]

Very good one, Hank! In an entire undergraduate program I dealt very little with effusion. Thanks for filling in my gaps; it's so relevant to real life!

[elizabethjaco]

These videos are literally the only reason I passed the AP chem test four years ago, and they're also the reason why I'm at the top of my class in college Chemistry.

[borisdorofeev]

Finally noticed Hanks tick. Left hand is constantly correcting his glasses, even though they aren't sliding off.

[goglebobo]

My brain gets all smug when Hank tells me all the things I've learned in each episode;)

[jaredjones]

What in the world??? @ 8:54 it says "NH3 + HCl3 ---> NH4Cl(s)" I know this is a mistake because Hank says Hydrochloric acid, the container is labeled HCl, and the above equation is not balanced.

[NitaJain]

Hank forgot to finish the problem at 6:45. The original question asked how LONG it will take for 1 L of Cl2 to effuse under identical conditions. Since the rate of effusion for Cl2 is 0.052L/min, it will take 19.23 minutes for 1 L of Cl2 to effuse.

[DaedricSheep]

using crash course to "study" for my chem final this semester. Not my best idea. Don't care. The textbook sucks.

[WilliamBlanks]

Getting almost an A+ in AP Chemistry.
I love you Hank.
<3

[reesetyra]

I noticed Mike Wasowski in one of the lockers of the animated school hallways (for those reading the comment section, he was in the lockers towards the right of the screen). But the science was cool too.

[shantellmclaggan]

i appreciate the Pokemon reference. Good video. :]

[missnailpolish]

Science, with added Niall... My favourite subject with a dash of my favourite Irishman, not complaining! Haha I'm actually loving this chemistry course, it's so much more understandable than I've even taught in the past!

[ellaschmidt]

Magic School Bus + Hank Green = everything beautiful in the world of science

[hawksish]

Crash Course is lying to you! The eggs aren't actually rotten! They would have a grayish discoloration which they clearly do not in the video #insidejob

[yuanyuansun]

Mistakes
1. "The velocity is proportional to the square root of the mass" -04:25( I think it should be inversely proportional)
2. "HCl3" -08:59( It should be HCl)

[ws]

so now the quandary is...
should I watch these here, where it's nice and safe and clean and playlisted, or should I watch these on khanacademy, where I will get points, but effort.

[cutoororoo]

As you might have GASSED,
Crash course videos are EGGcellent!!
P.S.HANK U R THE BEST!!