Hydrogen selenate

Several salts are explosively unstable, including hydrazinium azide (explodes on rapid heating or on initiation by a detonator, even when damp), chlorate (explodes at m.p., 80°C), chlorite (also highly flammable when dry), hydrogen selenate, hydrogen sulfate (explodes when melted), nitrate, nitrite, and the highly explosive perchlorate and diperchlorate used as propellants [1,2,3]. 

Hydrazinium hydrogen selenate, 4558 Hydrazinium nitrate, 4549 Hydrazinium nitrite, 4548 Hydrazinium perchlorate, 4011 Hydrazinium salts, 4546 See PROPELLANTS, REDOX COMPOUNDS... 

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

By the action of hydrazine hydrate on a dilute solution of selenic acid, hydrazine hydrogen selenate may be obtained as a colourless compound which is not decomposed by boiling water, but which, when dry, explodes with great readiness when subjected to heat, to shock, or to fumes of hydrogen chloride. For this reason, before hydrazine hydrate is used in the analysis of selenium compounds (see p. 307), it is essential that selenic acid and selenates should be reduced to selenites by means of hydrochloric acid.3... 

Hydrazinium hydrogen selenate, 4553 Hydrazinium nitrate, 4544 Hydrazinium nitrite, 4543... 

Diphenylhydrazinium chloride, 3513 Hydrazinium azide, 4545 Hydrazinium chlorate, 4004 Hydrazinium chloride, 4001 Hydrazinium chlorite, 4002 Hydrazinium dinitrate, 4556 Hydrazinium diperchlorate, 4062 Hydrazinium hydrogen selenate, 4553 Hydrazinium nitrate, 4544... 

Hydrazinium hydrogen selenate, 4553 Hydrazinium nitrate, 4544 Hydroxylaminium nitrate, 4519 2-Methoxyanilinium nitrate, 2825 l-Methyl-3-nitroguanidinium nitrate, 0943 Methylammonium chlorite, 0497 Methylammonium nitrate, 0503 Methylammonium nitrite, 0502 Methylhydrazinium nitrate, 0508 1-Phenylbiguanidinium hydrogen dichromate, 3014 Pyridinium nitrate, 1867... 

Caesium selenate, Cs2Se04. —The normal selenate has been obtained in rhombic crystals,4 of density 4-45285 at 20° C. At 12° C. its solubility is 245 grams in 100 grams of water. It is converted by selenic acid into caesium hydrogen selenate, CsHSe04.6... 

Ammonium selenates.—On evaporation, a solution of selenic acid saturated with ammonia yields the normal selenate, (NH4)2Se04, in monoclinic 7 crystals. At 7° C. its solubility is 117 grams in 100 grams of water.8 When gently heated, the normal salt is converted into ammonium hydrogen selenate, NH4HSe04,9 of density 2 162.10... 

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 ... 

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. 

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. 

SOB/SEL] Sobol, L. G., Selivanova, N. M., Heat of formation of sodium hydrogen selenate NaHSe04., Izv. Vyssh. Uchebn. Zaved, Khim. Khim. Tekhnol., 16, (1973), 1493-1495, in Russian. Cited on pages 422, 526, 540. 

Basically, such dependencies are also true of hydrogen selenates. However, it seems that the relations can be understood more easily, if the additional functions are subclassified in a not too detailed manner. Therefore, we want to confine our discussion of the Se-0 distances to the most important factors. 

Table 4 summarizes the Se-O distances in hydrogen selenates. Bond length data are given in colunms for different functions of the oxygen atoms which are listed below in the order of their decreasing influence on the Se-O bond length ... 

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