Example $3\mathrm{.}5$

Water is flowing past one of the rectangular sides of a slab of benzoic acid. The surface area exposed to water is $0\mathrm{.}01m^2$ and it is estimated that in $600$ seconds, $5{10}^{-4}kg$ of benzoic acid is lost from the slab by dissolution. If the molecular weight of benzoic acid is $121\mathrm{.}1k\frac{g}{k}g-$mol, calculate its average molar flux. If the solubility of benzoic acid in water is $0\mathrm{.}2k\frac{g}{m^3},$ what is its mass transfer coefficient? Assume that the concentration of benzoic acid in the bulk flowing water is negligible.