Standard Gibbs free energy of formation for Cu2O, NiO, CoO, and FexO: High resolution electrochemical measurements using zirconia solid electrolytes from 900-1400 K

Richard D. Holmes, Hugh St C. O'Neill, Richard J. Arculus

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Galvanic cells with oxygen-specific solid electrolytes made of calcia-stabilized zirconia have been used to make equilibrium measurements of the standard Gibbs free energy of formation, ΔfG0m,(T), for copper (I) oxide (Cu2O), nickel (II) oxide (NiO), cobalt (II) oxide (CoO), and wüstite (FexO) over the temperature range from 900-1400 K. The measured values of ΔfG0m at 1300 K are -73950, -123555, -142150, and -179459 J · mol-1 for Cu2O, NiO, CoO, and Fe0.947O, respectively. The precision of these measurements is ± 30-60 J · mol-1, and their absolute accuracy is estimated to be ± 100-200 J·mol-1. Using values of -76.557, -94.895, -79.551, and -71.291 J · K-1 · mol-1 for the entropies of formation, ΔfSm0, (298.15 K), the calculated enthalpies of formation, ΔfHm0, (298.15 K), are -170508, -240110, -237390, and -266458 J · mol-1 for Cu2O, NiO, CoO, and Fe0.947O, respectively. These values of ΔfSm0 (298.15 K) and ΔfHm0 (298.15 K) are in good agreement with the best available calorimetric measurements.

Original languageEnglish
Pages (from-to)2439-2452
Number of pages14
JournalGeochimica et Cosmochimica Acta
Issue number11
Publication statusPublished - Nov 1986
Externally publishedYes

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