Hydrogen selenate ion

The value of the protonation constant of the selenate ion, K, was varied systematically until a (reasonably) constant value of , independent of C, was obtained from the above equation. The result was log, = 2.0 and = — 0.1295 V. However, the equation is not quite correct as the degree of dissociation of the hydrogen selenate ion is substantially different in the two half-cells, cf. [35HAR/HAM]. The value obtained for Kx will therefore not be accepted. A recalculation of the data by the review has not been attempted. 

H0,Se 4 Hydrogen selenate ion (selenic acid) (Other values on Vol.4, p.93)... 

H2Se (hydrogen selenide, colorless), HSe (acid telluride ion, colorless), Se (selenide ion, colorless), H2Se03 (selenous acid, colorless), HSeOJ (acid selenite ion, colorless), SeO (selenite ion, colorless), H2Se04 (selenic acid, colorless), HSeOJ (acid selenate ion, colorless), SeO " (selenate ion, colorless). 

Ammonium Ion—cont d hydrogen selenate NH4HSe04 s white Sol ... 

The selected thermodynamic data for hydrogen selenate and selenate ions, with AfG° (HSe04,298.15 K) derived in Section V.3.4.2, would then be ... 

These results will be selected although it is not clear if a correction for the formation of hydrogen selenate was applied to the spectrophotometric data and the variation of the medium is considerable. The behaviour of the ion-selective electrode also poses questions on the reliability of the potentiometric data and hence the value of logio/ r at/=0. 

A unique acidic selenate is the mixed hydrogen selenate-diselenate Nd(HSe04)(Se207) (Wickleder, 2001). It is the only diselenate of the rare earth elements so far. In the crystal structure, Nd + is surrounded by six Se207 and three HSeOJ ions. The anions are monodentate and tricapped trigonal prisms [NdOg] are formed. These are linked to chains in di-... 

Wells and Salam have made extensive studies of the kinetics of the reaction between Fe and hydrogen peroxide in the presence of various anions. It was observed that the oxidation rate was unaffected by perchlorate and nitrate ions, whereas a large number of other anions including selenate changed the rate. These anions were all potential ligands and the following reaction scheme, somewhat simplified here, was proposed to account for the findings. It is written for SeO " but the same scheme applies to other anions as well ... 

Conditions such as pH (negative log hydrogen ion concentration), Eh (oxidation-reduction potential), and the presence of metal oxides affect the partitioning of the various compounds of selenium in the environment. In general, elemental selenium is stable in soils and is found at low levels in water because of its ability to coprecipitate with sediments. The soluble selenates are readily taken up by plants and converted to organic compounds such as selenomethionine, selenocysteine, dimethyl selenide, and... 

Bakker et al. [25] replaced the zinc in thermolysin with anions snch as molybdate, selenate, or tungstate to give an enzyme that catalyzed the nonenantioselective oxidation of thioanisoles with hydrogen peroxide. Van de Velde et al. [26] added a vanadate ion to the active site of phytase to create a catalyst for enantioselective oxididation of thioanisole to the sulfoxide in 66% ee. Selenosubtihsin (protease subtilisin where a selenoserine replaces the active-site serine) catalyzes the enantioselective reduction of hydroperoxides [27] with enantioselectivity >100 for one substrate. 

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