Transport and thermal properties of gases

The kinetic theory of gases has been used so far, the assumption being that gas molecules are non-interacting particles in a state of random motion. This 

Using the expressions given earlier for the mean velocity and the mean free patlr 

In a binary gas mixture, the diffusion coefficient of the species i at a mole fraction jc, widr respect to tlrat of the species j is given after evaluating the constants by tire equation 

An empu ical equation which has been found to be quite accurate (within 2%) was proposed by Andrussov (1950), which u, is the molar volume of tire ith species. 

This equation has a different temperature coefficient from that calculated from kinetic tlreory, and shows a shortcoming in the theory which is due to the assumption of non-interaction between the molecules. 

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