Q.5. Nitrogen from a gaseous phase is diffused into iron by a non-steady state diffusion at 675C that has already nitrogen impurity equal to one-tenth of the surface concentration. If the surface concentration is maintained at 0.5wt%N, what will be the concentration 2mm from the surface after 25h ? The diffusion coefficient for nitrogen in iron at 675C is 2.81011m2/s. CzC0CxC0=1erf(2Dtx)