Using a hydrocarbon gas to carburize the surface of a steel,…

Using a hydrocarbon gas to carburize the surface of a steel, we obtain a surface carbon content of 1.0 wt%. The initial carbon content of the steel is 0.2 wt%. How long (in HOURS) would take at 1000˚C to obtain a carbon concentration of 0.6 wt% at a distance 1.5mm from the surface? Given: Do = 20 x 10-6 m2/S; Q = 110 kJ/mol