In the high temperature combustion of coal in a power plant (1145K), the average size (diameter) of the coal particle is 0.02cm. For complete combustion, the reaction at the surface of the coal particle is 3C + 2O2 --> 2CO + CO2. Assuming that the combustion reaction is controlled by the diffusion of oxygen to the coal particle surface, estimate the instantaneous combustion rate of oxygen (mol/s) by the average size coal particle. Assume the diffusion coefficient of O2 at this temperature is 1.4 cm^2/s and that far away from the particle the partial pressure of O2 is 0.21 atm.