During "calcination of limestone, calcium carbonate is decomposed into lime and carbon dioxide. The rate of calcination is controlled by the rate of mass transport of CO2 from the surface of the solid to the surrounding atmosphere. Assume that the carbon dioxide diffuses through a stagnant film of air 1mm thick and that the concentration of carbon dioxide in the calcining furnace is zero.
From the data below, calculate the following
(a) The pressure of carbon dioxide at the surface of the limestone at 1000k.
(b) The rate of decomposition of limestone at 1000k (in moles per square meter of surface per second)
(c) Estimate the decomposition rate at 1100K.
DATA
For the reaction CaO+CO2--> CaCo3
ΔG= -161,300+137T J/mol
using P=1 atm as the standard state. Diffusion coefficient for CO2 in air at 1000K =4.7 x 10-4 m2/s