Peculiarities of CaCO3, SrCO3 and BaCO3 decomposition in CO2 as a proof of their primary dissociative evaporation

The results of thermogravimetric experiments on the decompositions of CaCO3, SrCO3 and BaCO3 in the presence of CO2 and some data reported in the literature were used for the determination of the E parameter of the Arrhenius equation by the third-law method. The values obtained (495, 569 and 605 kJ mol−1) are twice as much compared with the values of the E parameter obtained for these carbonates earlier in the absence of CO2. This fact together with the invariance of the E parameter with partial pressure of CO2 (PCO2) and a hyperbolic dependence of the rate of decomposition on PCO2 is in excellent agreement with the theoretical predictions deduced from the mechanism of decomposition that includes the primary stage of dissociative evaporation of reactant.