$9\mathrm{.}1-17.$ Unsteady$-$State Diffusion and Reaction. Solute $A$ is diffusing at

unsteady state into a semi$-$infinite medium of pure $B$ and undergoes a

first$-$order reaction with $B.$ Solute $A$ is dilute. Calculate the

concentration $c_A$ at points $z=0,4,$ and $10mm$ from the surface for $t$

$=1{10}^{5}s.$ Physical property data are $D_{AB}=1{10}^{-9}\frac{m^2}{s},k^{\text{'}}=1$

${10}^{-4}{s}^{-1},c_{A0}=1\mathrm{.}0$kgmo$\frac{l}{m^3}.$ Also calculate the kgmol

absorbed $\frac{?}{m^2}.$