Oxygen (A) is diffusing through carbon monoxide (B) via a rectangular plane surface between positions 1 and 2 under steady-state conditions, with the carbon monoxide non-diffusing. The total pressure is $1 \times 10^5\ \mathrm{N/m^2}$ and the temperature $0^\circ\mathrm{C}$. The partial pressure of oxygen at planes 1 and 2 is 13000 and 6500 $\mathrm{N/m^2}$, respectively. The two planes are 2 mm apart. The diffusivity for this mixture is $1.87 \times 10^{-5}\ \mathrm{m^2/s}$. Calculate the rate of diffusion of oxygen in kmol/s through each square meter of the two planes. The following data are provided: $R = 8314\ \mathrm{N\,m/(kmol\,K)}$.

Calculate the rate of diffusion of oxygen (A) under steady-state conditions and the same experimental conditions as the above part (a), but this time assuming that the non-diffusing gas is a mixture of methane (B) and hydrogen (C) under a volume ratio 2:1. Comment on this result with respect to those in part (a). The diffusivities of oxygen to hydrogen and methane are estimated to be $D_{O_2-H_2} = 6.99 \times 10^{-5}$ and $D_{O_2-CH_4} = 1.86 \times 10^{-5}\ \mathrm{m^2/s}$, respectively.