Chapter 05, Problem 5.14 An iron-carbon alloy initially containing 0.201 wt% C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1190°C. 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 0.0 wt% C. At what position will the carbon concentration be 0.151 wt% after a 7 h treatment? The value of D at 1190°C is 7.9 × 10-10 m2/s.

The concentration of Carbon will be 0.0% near the central surface of the alloy.

Explanation:

Iron makes alloy with carbon to form a compound called cementite i.e., Fe3C. Sometimes they combine to form steel and sometimes cast iron. The combination gives a cubic lattice in which carbon plays an important role as the central position taken by carbon and corner is from iron. At the place, The carbon will take the central surface position.

gravity causes stares to cluster i think so

it would be b. 6co2 + 6h2o --> c6h12o6 + 6o2