Computational prediction of the pattern of thermal gravimetry data for the thermal decomposition of calcium oxalate monohydrate

The multistep decomposition of CaC₂O₄·H₂O in the gaseous phase was explored at the MP2/cc-pVDZ level of theory. As a result, the structure and energy of the entities occurring at stationary points along the reaction pathway were determined. Statistical thermodynamics routines were used to obtain thermal energies/enthalpies and entropies. The results demonstrated the consecutive release of H₂O, CO and CO₂ from the substrate with increasing temperature. Moreover, the application of thermodynamic and kinetic characteristics to relevant phenomenological relationships enabled the decomposition pattern in equilibrium and non-equilibrium conditions to be predicted. The forecast patterns qualitatively match the experimental thermal gravimetry data. This study supplies much important information on the molecular changes taking place in a stoichiometric unit of calcium oxalate monohydrate during continuous heating