52. Solving a chemistry problem

2. Corrosion of a cobalt sample in air at 700 C is accompanied by a specific weight gain of 15 g/m2 in 1 hour. The activation energy of the process is 150 kJ/mol. Taking into account the parabolic law of scale growth, estimate the time during which a 1.5 mm thick cobalt plate is completely oxidized at 900 C. The corrosion product is CoO.