Thermodynamics
Mean Free Path
Average distance a molecule travels between collisions.
Variables
λm
Mean free path
Avg distance between collisions
k_BJ/K
Boltzmann constant
1.38×10⁻²³
TK
Temperature
Absolute temperature
dm
Molecular diameter
Effective diameter
PPa
Pressure
Gas pressure
Derivation
λ = 1/(√2 π d² n) where n = P/(kT).
Your notes
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Common questions
What is the Mean Free Path formula?
Mean Free Path is written λ= frac{k_B T}{√(2)πd² P}. Average distance a molecule travels between collisions. It belongs to Thermodynamics, under Kinetic Theory.
What are the units in λ= frac{k_B T}{√(2)πd² P}?
In SI units, λ is mean free path, measured in m; k_B is boltzmann constant, measured in kg·m²/(s²·K); T is temperature, measured in K; d is molecular diameter, measured in m; P is pressure, measured in kg/(m·s²).
How is the Mean Free Path formula derived?
λ = 1/(√2 π d² n) where n = P/(kT). The result is λ= frac{k_B T}{√(2)πd² P}.