Consider a DVD To protect sensitive information within the storage medium, a vwery thin film of reactive polymer is embedded within the polycarbonate at a distance of d= 0.5 mm from the surface. The thin film can undergo a chemical reaction with oxygen during which it is converted from a transparent material to an opaque material, rendering the information unreadable. The chemical reaction begins when the oxygen concentration at the reactive polymer reaches Ccrit = 5x10^5 kmol/m^3. The DVD is shipped in an oxygen-proof pouch; determine the elapsed time after removal from the pouch before the DVD self destructs. The solubility and diffusivity of oxygen in polycarbonate are S= 8.9x10^3 kmol/m3 ! bar and Dab=6.5x10^12 m^2/s, respectively.