In a liquid phase of solvent $"S"$ species $"A"$ reacts to form species $"B"$ at the

bottom catalytic surface $y=L.$ Species A and $B$ are assumed to be present in

small mole fractions, and ; thus $x_S$~~$1.$ The solvent is not moving

$N_s=0,$ but because of a heterogeneous reaction occurring at a surface $y=L($a

plane assumed to be infinite in extent$),$ species A and $B$ are moving in the $y$

direction $N_{By}0$;$N_{Ay}0$; their velocities in the $x$ and $z$ directions are equal to

zero. The reaction is assumed to be reversible with first order kinetics:

$A{}^{k_1}B$

$RB=-k_{-1}{C}_B(L)+k_1{C}_A(L)$

Here the rate of reaction is counted as positive when $"A"$ is consumed. Along the

plane $y=0$ in the solvent, the concentration of $"A"$ and $"B"$ are maintained to be

$C_{Ao}$ and $C_{Bo},$ respectively. Obtain the concentration distribution of A and $B$ and

the flux of $"A"$ at the surface $y=0.$