1. Gaseous hydrogen is stored at elevated pressure in a rectangular container having steel walls 10 mm thick. The molar concentration of hydrogen in the steel at the inner surface is 1 kmol/m?, while the concentration of hydrogen in the steel at the outer surface is negligible. The binary diffusion coefficient for hydrogen in steel is 0.26 x 10-12 m/s. Find the concentration profile of hydrogen and calculate the molar diffusion flux for hydrogen through the steel at a distance of 4 mm from the inner side