The concentration of zinc in a rod of brass is maintained at 10% at one end of a rod that is 0.01 m long; the other end is maintained at 0% by vaporizing the Zn as it arrives. At 500°C, the diffusion coefficient of Zn in brass is 4.10-17 m2.s-1. What is the flux of Zn moving down the rod? Write down all your assumptions (hint: you will need to look up the density of copper. You do not need to account for the variation in density with alloy composition). Explain what the boundary conditions were.