Example: In an air-carbon dioxide mixture at 298K and 202.6kPa, the concentration of CO2 at two planes (3mm) apart are 15 vol.\% and 25 vol.\%. The diffusivity of CO2 in air at 298K and 202.6kPa is 8.2106m2/s. Calculate the rate of transfer of CO2 across the two planes, assuming: a. Equimolecular counter diffusion. b. Diffusion of CO2 through a stagnant air layer