Modeling the Thermal Decomposition of Solids on the Basis of Lattice Energy Changes: Part 2: Alkaline–Earth Peroxides

In Part 1, the decompositions of the alkaline–earth metal (Ca, Sr, Ba) carbonates to their oxides, with the release of CO2gas, were modeled by devising a symmetry-based sequence of steps by which the reactant structure is converted to the product structure. Lattice energies were evaluated at each step to yield energy profiles for the postulated reaction processes. The observed (apparent) activation energies were comparable to the energy barriers for the postulated mechanisms, suggesting that the postulated mechanisms are energetically feasible. The calculations are repeated here (in Part 2) for the decompositions of the corresponding alkaline–earth peroxides. The energy barriers found are low compared to the observed activation energies. This result is taken to suggest that the postulated processes are energetically inaccessible.