A sheet of pure BCC iron, 1mm thick, was exposed to a carburizing gas atmosphere at 700 degrees Celsius while the other surface was exposed to a decarburizing gas (essentially a vaccuum). After reaching steady state the iron was quenched into water and the surface concentration of the iron exposed to the carburizing gas contained 0.001 weight percent carbon. If the diffusion flux is 1.0x10^-8 kg/m^2, calculate the diffusion coefficient of carbon in iron at 700 degrees Celsius.