Calculate the average distance between gas molecule collisions based on pressure and temperature.
Environmental Data
Results
Enter temperature, pressure, and diameter to calculate
About this calculator
Overview
In kinetic theory, the mean free path is the average distance a particle travels between successive collisions with other particles. It is a critical parameter in understanding gas transport properties like viscosity, thermal conductivity, and diffusion.
💡
Pro Tips
Units for temperature should be in Kelvin (K). T(K) = T(°C) + 273.15.
Collision diameter for common air molecules like Nitrogen (N₂) is approximately 0.37 nanometers (3.7 × 10⁻¹⁰ m).
As pressure decreases (e.g., in a vacuum), the mean free path increases significantly.
!
Fun Facts
"In the upper atmosphere (exosphere), the mean free path can exceed 10,000 kilometers."
"The 'Knudsen number' (Kn) compares the mean free path to a physical scale length to determine if the gas behaves as a fluid or as individual particles."
"If the mean free path is much larger than the equipment size, gas flow is called 'molecular flow', which is common in high-vacuum systems."
