A sheet of steel 2.5 mm thick has nitrogen atmospheres on both sides at 900 C and is permitted to achieve a steady-state diffusion condition. The diffusion coefficient for nitrogen in steel at this temperature is 1.2 x 10^-10 m^2/s, and the diffusion flux is found to be 1.0 x 10^-7 kg/m^2 s. Also, it is known that the concentration of nitrogen in the steel at the high pressure surface is 2 kg/m^3. How far into the sheet from this high pressure side will the concentration be .5 kg/m^3?