A thin plastic membrane is used to separate helium from a gas stream. Under steady-state conditions, the concentration of helium in the membrane is known to be 0.02 kg-mole/ m 3 and 0.005 kg-mole/ m 3...

A thin plastic membrane is used to separate helium from a gas stream. Under steady-state conditions, the concentration of helium in the membrane is known to be 0.02 kg-mole/ m³
and 0.005 kg-mole/ m³
at the inner and outer surfaces, respectively. If the membrane is 1 mm thick and the binary diffusion coefficient of helium with respect to the plastic is 10^–19
m²/s, what is the mass flux by diffusion ?