RT , i.e. ( P / P ) = ( µ / µ ). Here and refer to neon and oxygen respectively. Since ( P / P ) = ( / ) (given), ( µ / µ ) = / .
(i) By definition µ = ( N / N A ) and µ = ( N / N A ) where N and N are the number of molecules of and , and N A is the Avogadro’s number. Therefore, ( N / N ) = ( µ / µ ) = / . (ii) We can also write µ = ( m / M ) and µ = ( m / M ) where m and m are the masses of and ; and M and M are their molecular masses. (Both m and M ; as well as m and M should be expressed in the same units).
If ρ and ρ are the mass densities of and respectively, we have ρ ρ µ µ × / / . . . .
KINETIC THEORY OF AN IDEAL GAS Kinetic theory of gases is based on the molecular picture of matter. A given amount of gas is a collection of a large number of molecules (typically of the order of Avogadro’s number) that are in incessant random motion. At ordinary pressure and temperature, the average distance between molecules is a factor of or more than the typical size of a molecule ( Å). Thus, interaction between molecules is negligible and we can assume that they move freely in straight lines according to Newton’s first law.
However, occasionally, they come close to each other, experience intermolecular forces and their velocities change. These interactions are called collisions. The molecules collide incessantly against each other or with the walls and change their velocities. The collisions are considered