Emf measurements of the following galvanic cells were carried out to determine the standard molar Gibbs energies of formation of Sb₂O₃, ZnSb₂O₄ and MgSb₂O₄:
(−) Pt, Re|Sb, Sb₂O₃|ZrO₂+Y₂O₃|air, Pt (+),
(−) Pt, Re|Sb, ZnO, ZnSb₂O₄|ZrO₂+Y₂O₃|air, Pt (+) and
(−) Pt, Re|Sb, MgO, MgSb₂O₄|ZrO₂+Y₂O₃|air, Pt (+).
The results were represented as follows:
1. ΔG⁰⁄kJ±0.47=−686.2+0.2422T⁄K (T⁄K<904),
ΔG⁰⁄kJ±0.70=−643.1+0.1951T⁄K (904<T⁄K<929) and
ΔG⁰⁄kJ±0.53=−687.8+0.2433T⁄K (929<T⁄K)
for 2Sb(s, l)+3/2O₂(g)=Sb₂O₃(s, l).
2. ΔG⁰⁄kJ±0.70=−170.4+0.2574T⁄K (T⁄K<904)
for 2Sb(s)+3/2O₂(g)+ZnO(s)=ZnSb₂O₄(s).
ΔG⁰⁄kJ±0.35=−739.5+0.2869T⁄K (T⁄K>904)
for 2Sb(l)+3/2O₂(g)+ZnO(s)=ZnSb₂O₄(s).
ΔG⁰⁄kJ±1.2=27.0−0.0153T⁄K (T⁄K<904),
ΔG⁰⁄kJ±1.1=96.4−0.0918T⁄K (904<T⁄K<929) and
ΔG⁰⁄kJ±0.9=51.8−0.0435T⁄K (929<T⁄K),
for Sb₂O₃(s, l)+ZnO(s)=ZnSb₂O₄(s).
3. ΔG⁰⁄kJ±0.53=−745.6+0.2720T⁄K (945<T⁄K<1117)
for 2Sb(l)+3/2O₂(g)+MgO(s)=MgSb₂O₄(s).
ΔG⁰⁄kJ±1.1=−58.0+0.0287T⁄K (945<T⁄K<1117)
for Sb₂O₃(l)+MgO(s)=MgSb₂O₄(s).