1. Oxygen gas is maintained at pressures of 2 bars and 1 bar on opposite sides of a rubber membrane that is 0.5 mm thick, and the entire system is at 25°C. What is the molar diffusive flux of O2 through the mem- brane? What are the molar concentrations of O2 on both sides of the membrane (outside the rubber)?
2. Insulation degrades (experiences an increase in thermal conductivity) if it is subjected to water vapor condensa- tion. The problem may occur in home insulation during cold periods, when vapor in a humidified room diffuses through the drywall (plaster board) and condenses in the adjoining insulation. Estimate the mass diffusion rate for a 3 m X 5 m wall, under conditions for which the vapor pressure is 0.03 bar in the room air and 0.0 bar in the insulation. The drywall is 10 mm thick, and the solubility of water vapor in the wall material is approximately 5 X 10-3 kmol/m3 · bar. The binary diffusion coefficient for water vapor in the drywall is approximately 10-9 m2/s.