Calculating Mean Free Path of N2 Molecule in UHV Chamber

[albega]

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...

 

[Bystander]

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?

 

[albega]

Standard temperature, 0degc. Thanks.