Nitrogen from a gaseous phase is to be diffused into pure iron at 700C. If the surface concentration is maintained at 0.26 wt% N, what will be the concentration (in weight percent) 2.8 mm from the surface after 7.8 h? The diffusion coefficient for nitrogen in iron at 700C is 1.8 x 10-10 m/s. Z erf(z) z erf(z) z erf(z) 0.00 0.0000 0.55 0.5633 1.3 0.9340 0.025 0.0282 0.60 0.6039 1.4 0.9523 0.05 0.0564 0.65 0.6420 1.5 0.9661 0.10 0.1125 0.70 0.6778 1.6 0.9763 0.15 0.1680 0.75 0.7112 1.7 0.9838 0.20 0.2227 0.80 0.7421 1.8 0.9891 0.25 0.2763 0.85 0.7707 1.9 0.9928 0.30 0.3286 0.90 0.7970 2.0 0.9953 0.35 0.3794 0.95 0.8209 2.2 0.9981 0.40 0.4284 1.0 0.8427 2.4 0.9993 0.45 0.4755 1.1 0.8802 2.6 0.9998 0.50 0.5205 1.2 0.9103 2.8 0.9999