Intrinsic kinetics of the thermal decomposition of sodium bicarbonate

The intrinsic kinetics of the thermal decomposition of NaHCO₃ to Na₂CO₃ has been studied by non-isothermal thermogravimetric analysis. NaHCO₃ powder of 47 μm mean particle size was heated to decomposition at three constant heating rates (1.25, 2.5, and 5° C min^-1) in flowing nitrogen. The range in which the decomposition occurred was about 360-450 K. A graphical method and Friedman's method were both used to analyze the experimental data: close agreement was obtained. The reaction rate showed a first-order dependence on the amount of unreacted NaHCO₃ and the values for the activation energy and pre-exponential factor were 25.3 kcal mol^-1 (105.8 kJmol^-1) and 6.7 × 10¹² min^-1, re- spectively.