1. The problem statement, all variables and given/known data Estimate the mean free path of an electron in mercury vapour at a temperature of 160 degrees C, where the vapour pressure is 11.28 mmHg It gives the standard atmospheric pressure as 761.84 mmHg. 2. Relevant equations Mean free path= (Boltzmann's constant times temperature)/(sqrt(2)*pi*(d^2)*p) where d is the diameter of the molecule and p is the pressure. 3. The attempt at a solution I have: Boltzmann's constant= 1.38x10^-23 T=273+160=433K d=302x10^-12 metres p=(11.28/761.84)*101325 Pa (I think these are all the right units to use) So I fill these into the formula and get 9.834x10^-6 m as my value for mean free path. I have nothing to compare this to, so I have no idea whether this is right or way off the mark.