Plot the mass diffusivity, DAB, versus the molecular weight of Substance A for Substance B being air at p = 1.5 atm, T = 320 K. Substance A is each of the first 8 entries of Table A.8. Is your plot consistent with kinetic theory? Consult various sources, including Table A.4 and Example 6.2 for molecular weight values.

Example 6.2

A long circular cylinder 20 mm in diameter is fabricated from solid naphthalene, a common moth repellant, and is exposed to an airstream that provides for an average convection mass transfer coefficient of h_m = 0.05 m/s. The molar concentration of naphthalene vapor at the cylinder surface is 5 X 10^–6 kmol/m3, and its molecular weight is 128 kg/kmol. What is the mass sublimation rate per unit length of cylinder?