An FCC iron-carbon alloy initially containing 0.55 wt% C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1325 K. Under these circumstances, the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere -- that is, the carbon concentration at the surface position is maintained essentially at 0 wt% C. This process of carbon depletion is called decarburization. At what position will the carbon concentration be 0.20 wt% after 10 h treatment?

The heater element of a 120 v toaster is a 5.4 m length of nichrome wire, whose diameter is 0.48 mm. the resistivity of nichrome at the operating temperature of the toaster is 1.3 × 10-6 ω·m. the toaster is operated at a voltage of 120 v. (a) what is the power drawn by the toaster? (b) if the cost of electricity is 12 ¢ per kilowatt-hour, and it takes 2 minutes to toast bread, how much does it cost for toasted bread? (c) when the heater element is at room temperature, is the resistivity in the nichrome wire greater than, less than, or equal to it’s resistivity when at operating temperature? explain.