Mean Activity Coefficients of Peroxodisulfates in Saturated Solutions of the Conversion System 2NH4+ — 2Na+ — S2O82– — SO42– — H2O at 20 °C and 30 °C

Solubility data of the conversion system 2NH₄⁺ - 2Na⁺ - S₂O₈^2- - SO₄^2- - H₂O at 20 °C and 30 °C for the partial pseudoternary systems Na2S2O8-(NH4)2SO4-H2O, (NH4)2S2O8-Na2SO4-H2O, Na₂S₂O₈-NaNH₄SO₄-H₂O and (NH₄)₂S₂O₈-NaNH₄SO₄-H₂O have been correlated using the relative activity coefficient expansion of the crystallizing component. The obtained correlation equations have been used for the calculation of mean activity coefficients of ammonium and sodium peroxodisulfates in their saturated solutions of the mentioned pseudoternary systems.