Question

Find the mean free path and the mean time interval between successive collisions of gaseous nitrogen molecules
(a) under standard conditions ,
(b) at temperature `t = 0 ^@C` and pressure `p = 1.0 nPa` (such a pressure can be reached by means of contemporary vacuum pumps).

Answer 1

(a) `lamda = (1)/(sqrt(2) pi d^2 n) = (kT)/(sqrt(2) pi d^2 p)`
=`(1.38 xx 10^-23 xx 273)/(sqrt(2) pi (0.37 xx 10^-9)^2 xx 10^5) = 6.2 xx 10^-8 m`
`tau = (lamda)/(lt v gt) = (6.2 xx 10^-8)/(454) s = 136 n s`
`lamda = 6.2 xx 10^6 m`
(b) `eta = 1.36 xx 10^4 s = 3.8` hours.