Consider the steady, uni-directional diffusion of a binary mixture of \( A \) and \( B \) across a vertical slab of dimensions \( 0.2 \, \text{m} \times 0.1 \, \text{m} \times 0.02 \, \text{m} \) as shown in the figure. The total molar concentration of \( A \) and \( B \) is constant at \( 100 \, \text{mol} \, \text{m}^{-3} \). The mole fraction of \( A \) on the left and right faces of the slab are maintained at \( 0.8 \) and \( 0.2 \), respectively.
If the binary diffusion coefficient \( D_{AB} = 1 \times 10^{-5} \, \text{m}^2 \, \text{s}^{-1} \), the molar flow rate of \( A \) in \( \text{mol} \, \text{s}^{-1} \), along the horizontal \( x \)-direction is:
\includegraphics[width=0.5\linewidth]{q17 ce ..PNG}