Diffusivities in air

Estimate the diffusivity of the 10 compounds from problem 3 at 1°C. Compare and explain the importance of temperature to diffusion in water versus the importance of temperature to diffusion in air. 

Illustrative Example 18.1 Estimating Molar Volumes Illustrative Example 18.2 Estimating Molecular Diffusivity in Air Diffusivities in Water... 

Illustrative Example 18.2 Estimating Molecular Diffusivity in Air Problem Estimate the molecular diffusion coefficient in air, >,a, ofCFC-12 (see Illustrative Example 18.1) at 25°C (a) from the mean molecular velocity and the mean free path, (b) from the molar mass, (c) from the molar volume, (d) from the combined molar mass and molar volume relationship by Fuller (Eq. 18-44), (e) from the molecular diffusivity of methane. 

Explain qualitatively the semiempirical relation of Fuller et al. (1966) for molecular diffusivity in air (Eq. 18-44). How is this expression related to the molecular theory of gases ... 

What makes diffusion through a porous medium different How do the relevant effects differ for diffusion in air and in water, respectively ... 

To this end we use the boundary models derived in Chapter 19. Since each model has its own characteristic dependence on substance-specific properties (primarily molecular diffusivity in air or water), the experimental data from different compounds help us recognize the strengths and limitations of the various theoretical concepts. 

To calculate v/a from vwaler3 we use Eq. 20-27 and the simple molar mass relationship (Eq. 18-45) to estimate molecular diffusivity in air, Di3 ... 

Where does molecular diffusion (in air or water) actually play a role in the environment Give reasons why it is not relevant in systems which you exclude in your answer. 

This study comprised the first reported direct experimental measurement of surface diffusion in air-suspended thin liquid films. 

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