Constantes d'acidite de l'acide pyrophosphorique et constantes de stabilite des complexes avec le potassium et le sodium: en|The acidity constants of pyrophosphoric acid and the stability constants of complexes with potassium and sodium ions

(The acidity constants of pyrophosphoric acid and the stability constants of complexes with potassium and sodium ions)The effect of potassium and sodium ions on the acidity constants of pyrophosphoric acid is studied by potentiometry at 25°C and at an ionic strength of 0.5 mol l^-1. Comparison of the results obtained in potassium chloride or sodium chloride medium with those found in tetramethylammonium chloride medium provides evidence of the formation of potassium and sodium complexes of the type MHP₂O^2-₇ and MP₂O^3-₇. Stability constants of these complexes are calculated and distribution diagrams of the species as a function of pH are given for the three different media utilized.