A thin plastic membrane is used to separate helium from a gas stream. Under steady state, the concentration of helium in the membrane is 0.02 and 0.005 kmol/m 3 at the inner and outer surfaces,...

A thin plastic membrane is used to separate helium from a gas stream. Under steady state, the concentration of helium in the membrane is 0.02 and 0.005 kmol/m³ at the inner and outer surfaces, respectively. If the membrane thickness is 1 mm and the binary diffusion coefficient of helium with respect to the plastic is 10^-9 m²/s, what is the diffusive molar flux? Assume one-dimensional transport.