A 0.001 in. BCC iron foil is used to separate a high hydrogen content gas from a

Question:

A 0.001 in. BCC iron foil is used to separate a high hydrogen content gas from a low hydrogen gas at 650 °C. 5 × 108 H atoms/cm3 are in equilibrium on one side of the foil, and 2 × 103 H atoms/cm3 are in equilibrium with the other side.
Determine
(a) The concentration gradient of hydrogen; and
(b) The flux of hydrogen through the foil.