It is desired to calculate the rate of diffusion of CO2 gas in air at steady state through a loosely packed bed of sand at 276 K and a total pressure of 1.013 × 10 5 Pa. The bed depth is 1.25 m and the void fraction ε is 0.30. The partial pressure of CO2 is 2.026 × 10 3 Pa at the top of the bed and 0 Pa at the bottom. Use a τ of 1.87.