Activity and Osmotic Coefficients from the Emf of Liquid-Membrane Cells. VII: Co(ClO4)2, Ni(ClO4)2, K2SO4, CdSO4, CoSO4, and NiSO4

The activity coefficients of CdSO₄ CoSO₄, and NiSO₄ are determined from the emf of liquid-membrane cells, like those described in the papers I–VI of this series. The activity coefficients of the auxiliary salts Co(ClO₄)₂, Ni(ClO₄)₂, and K₂SO₄, needed to eliminate the problem of extrapolation to infinite dilution of the 2–2 salts, are also measured. CdSO₄ CoSO₄ and NiSO₄ in the dilute region deviate downward from the limiting law by a larger extent than believed in the past, thus creating the need for the activity coefficients to be recalculated and systematically lowered by 8–16%. The activity coefficients of Co(ClO₄)₂ and Ni(ClO₄)₂, too, need to be corrected by around –3%. For K₂SO₄, the original values, although scattered, were substantially correct. Pitzer's theory best-fit parameter, able to provide the activity and osmotic coefficients of the salts considered, are reported.