Estimate the mean free path for a water molecule in water vapour at 373.The diameter of the molecule is 2xx10^(10)m, and at STP number of molecules per unit volume is 2.7xx10^(25)m^(-3)

Estimate the mean free path for a water molecule in water vapour at 37

1.	Estimate the mean free path for a water molecule in water vapour at 373.The diameter of the molecule is 2xx10^(10)m, and at STP number of molecules per unit volume is 2.7xx10^(25)m^(-3)
Answer» Solution :The number DENSITY (n) is inversely proportional to absolute temperature. `therefore nalpha(1)/(T)implies(n_(273))/(n_(273))=(273/(373)),n_(373)=n_(273)xx(273)/(373)` `n_(373)=2.7xx10^(25)xx(273)/(373)=2xx10^(25)m^(-3)` Given d=`2xx10^(-10)m` Hence ,mean FREE path `LAMBDA=(1)/(sqrt(E)pid^(2)n)` `=(1)/(sqrt(2)xx3.14xx(2xx10^(-10))^(2)xx2xx10^(25))=4xx10^(-7)m`