# Calculating Mean Free Path of N2 Molecule in UHV Chamber

• albega
In summary, the mean free path of an N2 molecule in an ultra-high-vacuum chamber at a pressure of 10-10mbar can be calculated using the equation λ=kT/(√2)πpd2, where n is the number density, σ is the collision cross-section, p is the pressure, and d is the molecular diameter. While the temperature T is not given, it can be assumed to be a standard value such as 0°C for reference data.

## Homework Statement

What is the mean free path of an N2 molecule in an ultra-high-vacuum chamber at a pressure of 10-10mbar?

## Homework Equations

λ=1/(√2)nσ
number density n, collision cross-section σ
p=nkT
pressure p, temperature T
σ=πd2
d molecular diameter

## The Attempt at a Solution

λ=kT/(√2)πpd2
where we know p and I can estimate d to be around 10-10m. However I am not given T, and I don't really see how I could know what it is...

albega said:
However I am not given T, and I don't really see how I could know what it is.
At which point, you're free to assume a temperature. What's a good standard temperature for reference data?

Standard temperature, 0degc. Thanks.

## What is the mean free path of a N2 molecule?

The mean free path of a N2 molecule is the average distance a molecule travels between collisions in a vacuum chamber.

## How is the mean free path of a N2 molecule calculated?

The mean free path of a N2 molecule can be calculated using the formula: λ = kT / √(2) * π * d^2 * P, where λ is the mean free path, k is the Boltzmann constant, T is the temperature, d is the molecular diameter, and P is the pressure.

## Why is it important to calculate the mean free path of N2 molecules in a UHV chamber?

It is important to calculate the mean free path of N2 molecules in a UHV chamber because it helps in understanding the behavior of gas molecules in the chamber and can aid in optimizing experimental conditions for various processes.

## What factors can affect the mean free path of N2 molecules in a UHV chamber?

The mean free path of N2 molecules in a UHV chamber can be affected by factors such as temperature, pressure, and the size of the chamber. Higher temperatures and lower pressures can result in longer mean free paths, while a smaller chamber size can decrease the mean free path.

## Can the mean free path of N2 molecules in a UHV chamber be experimentally measured?

Yes, the mean free path of N2 molecules in a UHV chamber can be experimentally measured using techniques such as laser absorption spectroscopy or gas flow measurements.