Potentiometrische säure-base-titrationen in alkalisulfatschmelzen

Using the Pt-(O₂) electrode as an indicator electrode for the O^2? concentration of a sulphate melt, potentiometric acid-base titrations have been carried out at 625°C in the eutectic Li₂SO₄-K₂SO₄-Na₂SO₄ melt. Na₂CO₃ has been used as an O^2? donor, and MoO₃, K₂Cr₂O₇, NaPO₃, Na₄P₂O₇ and V₂O₅ were used as acid species. While the equivalence point is at an acid/Na₂CO₃ molar ratio of 1:1 with MoO₃, K₂Cr₂O₇, NaPO₃ and Na₄P₂O₇, it is situated at about 0.3:1 in the system V₂O₅/Na₂CO₃.