Terms and Formulae
Terms
Boltzmann constant
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A constant, k, involved in the equation for average velocity. k = 1.38×10-23 J/K
Diffusion
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Diffusion is the spread of one substance through another.
Effusion
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Effusion is the rate at which a gas passes through a small hole into a vacuum.
Kinetic energy
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Ek = 1/2mv2
Kinetic molecular theory
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A theory that models the interaction between individual gas molecules. See the
summary
for more details.
Maxwell-Boltzmann speed distribution
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The distibution attained when molecule speed is set against the number of molecules sharing that speed.
Mean free path
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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
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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
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An equation to measure the typical velocity of molecules in a gas.
Formulae
Average velocity 
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Kinetic energy
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Ek = 1/2mv2
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Mean free path
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| λ = |
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Formule for most probable velocity
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| vp = = |
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Formula for root mean square velocity
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= 
= 
