Sodium Scandium Selenates

2 Sodium Rare Earth Selenates Sodium Scandium Selenates Na3Sc(Se04)3 

The anhydrous double selenate is formed on heating the pentahydrate at 231°C. For details and IR spectrum, see p. 506, Khayasi Tetsu et al. [1]. 

The results show that Na38c(8e04)3 in dilute solutions behaves as a complex with a stable [80(8004)3] ion and A corresponds to that of a four-ion electrolyte. Comparison is made with the sulfate [2]. 

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The complex formation between Sc and SeOj" was studied by measurement of the distribution of Sc between the aqueous phase and a cation exchanger at selenate concentrations in the range 0 to 0.167 M. Sodium perchlorate was added to keep the ionic strength at / = 0.5 M. The radioactive nuclide Sc was used to follow the distribution ratio at a total scandium concentration of 2 x 10 M. Measurements were carried out at 298.15, 308.15, and 318.15 K and the pH was adjusted to 4.0 to 4.5. No disturbance from the hydrolysis of Sc occurs at this pH according to the paper although this would be expected from the data in [76BAE/MES]. 

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