Carbon dioxide is formed during the combustion of a pure carbon sphere in a flowing stream of oxygen gas at 1100°C and 1 atm. of total pressure. C+0₂ → CO₂ Calculate the time of sublimation of 60 % of...

Carbon dioxide is formed during the combustion of a pure carbon sphere in a flowing stream of oxygen gas at 1100°C and 1 atm. of total pressure.

C+0₂ → CO₂

Calculate the time of sublimation of 60 % of the mass of a 15 mm diameter of the sphere of pure carbon in the oxygen gas stream, if the sphere is always surrounded by a 4 mm thick stagnant film of oxygen stream. The diffusivity of CO₂ in O₂ under given conditions is 3.4 cm²/s, the density of carbon sphere is 900 kg/m³ and the partial pressure of CO₂ in the bulk is 0.4 atm. Also calculate the rate of combustion of carbon sphere.