• ### Boltzmann constant

A constant, k, involved in the equation for average velocity. k = 1.38×10-23 J/K

• ### Diffusion

Diffusion is the spread of one substance through another.

• ### Effusion

Effusion is the rate at which a gas passes through a small hole into a vacuum.

Ek = 1/2mv2

• ### Kinetic molecular theory

A theory that models the interaction between individual gas molecules. See the summary for more details.

• ### Maxwell-Boltzmann speed distribution

The distibution attained when molecule speed is set against the number of molecules sharing that speed.

• ### Mean free path

The mean distance a molecule travels before it impacts another molecule; given the huge number of collisions in a gas, the mean free path is vastly smaller than any typical room or container. The equation for mean free path:

 λ = • ### mp

The most probable velocity at which the most molecules in a gas travel. The formula for most probable velocity is:

 vp = = • ### Root mean square velocity

An equation to measure the typical velocity of molecules in a gas.

 vrms = = = • #### Formulae

Average velocity  = = Kinetic energy Ek = 1/2mv2

Mean free path

 λ = Formule for most probable velocity

 vp = = Formula for root mean square velocity

 vrms = = = 