Estimation of diffusivity in a gas mixture at low density

Example 2.12 Estimation of diffusivity in a gas mixture at low density Estimate the diflusivity of benzene in air at 25°C and 1 atm. 

Use the Chapman-Enskog equation for the binary diffusivity at low density (Eq. 2.72)  

At low pressures, we use the following expression developed from a combination of kinetic theory and corresponding states approach to estimate the effect of temperature on diffusivity  

We can use the following empirical relation for estimating the critical self-diffusivity between / and labeled species (cDa.)c  

Here the c-multiplied diffusion coefficients are used because their dependence on pressure and temperature is simpler, and they are frequently used in mass transfer calculations. 

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