Deduce Graham's law from kinetic gas equation.

Explanation

Graham's law: According to kinetic gas equation , `PV =1/3 mnc^2`
(or) `PV=1/3 mnc^2 (or) c^2=(3PV)/m` But `V/m=1/d`
`therefore c^2=(3P)/d (or) c=sqrt((3P)/d)`
At constant pressure,
c= constant `times 1/sqrtd` (or) `c=1/sqrtd`
In the case of gases r.m.s velocity (c) is directly proportional to rate of diffusion (r).
`therefore r prop 1/sqrtd` (At constant T and P)
i.e., At constant temperature and pressure the rate of diffusion of a gas is inversely proportional to the square root of its density . This is Graham's law.