Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Mean free path is the average distance a gas molecule travels between collisions with other molecules. It is influenced by factors such as temperature, pressure, and particle size.
5 Must Know Facts For Your Next Test
Mean free path decreases with increasing pressure because more molecules are present, leading to more frequent collisions.
An increase in temperature generally increases the mean free path because molecules move faster and collide more energetically.
Mean free path is inversely proportional to the density of the gas; higher density results in a shorter mean free path.
The formula for mean free path $\lambda$ is given by $\lambda = \frac{k_B T}{\sqrt{2} \pi d^2 P}$ where $k_B$ is Boltzmann's constant, $T$ is temperature, $d$ is the diameter of the molecules, and $P$ is pressure.
Mean free path plays a crucial role in understanding diffusion and effusion processes in gases.
The spreading of gas molecules throughout a container until evenly distributed due to random molecular motion.
Boltzmann's Constant: $k_B$, a fundamental physical constant that relates energy at the individual particle level with temperature. Its value is approximately $1.38 \times 10^{-23} \text{J/K}$.