Terms and Formulae
Terms
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.
Kinetic energy
 E_{k} = 1/2mv^{2}
Kinetic molecular theory

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

m_{p} 
The most probable velocity at which the most molecules in a gas travel. The formula for most probable
velocity is:
v_{p} = = 

Root mean square velocity

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

Kinetic energy
 E_{k} = 1/2mv^{2} 
Mean free path

λ = 


Formule for most probable velocity

v_{p} = = 


Formula for root mean square velocity

