Graham's Law

Created By: Erin Damerell

Equation for finding the number of times one gas effuses faster than another gas is....

Basically, take the square root of the heavier gas and divide it by the square root of the lighter gas. Most likely your answer will be a square root, so don't forget to turn it into a decimal!

Graham's Law Jargon

Diffusion: gases in higher concentration move to lower concentration, if possible.

Effusion: when gases escape through a small opening in a container.

Another small fact: big fat gass particles go slow and little skinny gass particles go fast.


To the right is a visual aid of how Grahmah's Law works. All the particals started in the left side, however the rift between the two boxe caused some of the particals to zoom over into the right box! Can you guess why? If you say that it's a result of diffusion than you're right!

Practical Application

Graham's law is so, so much fun right? But you're probably thinking, "What on Earth would I use this for?" Well, the next time you deicde to slash somebody's tire because they're making you made you can use Graham's Law to understand why the tire deflates. You see, slicing/poking/stabbing a tire creats a hole. Since the pressure inside the tire is higher than the pressure outside the tire the particales go zooming out, this is called effusion.