A membrane dialyzer $($artificial kidney$)$ is used to remove urea from the blood. The bulk concentration in the urea in the blood is $2{10}^{-4}\frac{g}{c}m3.$ The bulk concentration of urea in the aqueous phase downstream from the membrane can be taken as zero. The mass transfer coefficients in the blood and aqueous phase are $k_1=1\mathrm{.}1{10}^{-5}\frac{m}{s}$ and $k_2=4\mathrm{.}5{10}^{-5}\frac{m}{s}$ respectively. The membrane thickness is $1{10}^{-5}m$ and its permeability to urea is $2\mathrm{.}5{10}^{-10}\frac{m^2}{s}.$

a$.)$ What is the flux of urea in $\frac{g}{c}{m}^{2}s?$

b$.)$ What is the concentration of urea in the blood at the membrane surface in $\frac{g}{c}{m}^3?$

c$.)$ What is the concentration of urea in the aqueous phase at the membrane interface in $\frac{g}{c}{m}^3?$