Thermodynamics of Fe oxides: Part II. Enthalpies of formation and relative stability of goethite ({alpha}-FeOOH), lepidocrocite ({gamma}-FeOOH), and maghemite ({gamma}-Fe2O3)

摘要

The enthalpy of formation from the elements at 298.15 K (H0_f) of lepidocrocite (-FeOOH) and maghemite (-Fe₂O₃) has been measured by acid-solution calorimetry as –549.4 ± 1.4 and –808.1 ± 2.0 kJ/mol, respectively. The H_f0 of goethite (-FeOOH) was measured by high-temperature transposed temperature drop and acid-solution calorimetry as –559.5 ± 1.1 and –560.7 ± 1.2 kJ/mol, respectively.