Aqueous nickel II sulphato complexes

Method t/°C Medium (aq) Reported value Recalculated value Reference 

As discussed in Appendix A, it appears that the reported molar conductance values from at least two of the studies [73KAT], [76SHI/TSU] are for rounded concentration values. If the values reported are smoothed molar conductances, the true experimental scatter may have been greater. The statistical uncertainties listed in Table V-25 are the values from the data re-analysis [80PET/TAB]. Fitting of the (unavailable) primary data from those studies probably would have led to larger calculated statistical uncertainties in (assumed equivalent to AT°(V.88)). Estimated (2a) uncertainties for all four values of Ai°((V.88), 298.15 K) are listed in Table V-25. Based solely on the conductance data at 25°C, at 7 = 0 the value of Ai°((V.88), 298.15 K) is (228.1 15.5), or log,o 7 ((V.88), 298.15 K) = (2.36 0.03). 

Earlier reviews [82WAG/EVA], [99ARC] gave substantial weight to the emf study of Nair and Nancollas [59NAI/NAN]. As shown in Appendix A, recalculation of values from that study to be consistent with the SIT procedure described in Appendix B, requires values for the dissociation constant of HSO, and several interaction coefficients, e(Ni, Cl), (H, C1), e(H, HSO ) and e(Ni, FISO ). The values calculated for the formation constant of NiS04(aq) are extremely sensitive to the activity coefficient model, to the values used for the interaction coefficients and to the values assumed 

If the estimated uncertainty bounds are considered, the value from Nair and Nancollas overlaps with those from the conductance studies. Using the weighted average of the conductance and emf data ((228.1 + 15.5) and (173 80), respectively, weighted according to their uncertainties), the selected value of AT°((V.88), 298.15 K) is  

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