Nickel selenates

Klein [40KLE] measured the solubility of nickel selenate in water as a function of temperature and presents the results in a table and a graph. The hexahydrate, NiSe04-6H20, is the stable phase below 355 K and NiSe04-4H20 above this temperature. 

The review selects the greater value from the fact that Ojkova, who is the coauthor of papers belonging to both sets, uses this datum in her later publications  

The value of solubility product of NiSe04-6H20(cr) at 298.15 K, NiSe04-6H20(cr) Np + SeOj + 6H20(1) 

The standard Gibbs energy of formation of NiSe04-6H20(cr) is calculated from the Gibbs energy of Reaction (V.126) and the values of AfC° for the ions and water to be  

Ghosh and Nair [70GHO/NAI] determined the equilibrium constant of the re- 

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Nickel Selenate, NiSe04.6H20, may be obtained as green octahedral crystals by allowing a solution of nickel carbonate in selenic acid to evaporate slowly at ordinary temperature.4... 

Christov calculated the parameters in the Pitzer ion interaction model from isopiestie measurements at 298.15 K by Ojkova and Staneva [890JK/STA]. This reference contains (interpolated) osmotic coefficients of zinc, magnesium, cobalt, and nickel selenate solutions from 0.1 mol-kg to saturated solution. Sodium chloride standards were used and the agreement between duplicate determinations was 0.2% or better. 

The result for nickel selenate has been revised in later publications [980JK/CHR], [2001BAR/CHR]. 

The paper also contains a calculation of the Pitzer coefficients of nickel selenate solutions from isopiestic measurements by Ojkova and Staneva [890JK/STA]. The results contained in Table A-122 also appear in [98CHR/OJK], [2001BAR/CHR],... 

JK/ST0] Ojkova, T. G., Stoilova, D. G., Staneva, D. 1., Thermodynamical study of the zinc selenate-nickel selenate-water system at 25 C, Bulg. Chem. Commun., 26, (1993), 259-267. Cited on pages 263, 264,314. 

Thermodynamical study on the magnesium selenate-nickel selenate-water system at 25°C, Monatsh. Chem., 126, (1995), 535-541. Cited on page 314. 

JK/CHR] Ojkova, T., Christov, C., Mihov, D., Investigation of the aqueous lithium and nickel selenate system, Z. Phys. Chem. (Munich), 203, (1998), 87-93. Cited on pages 314,415, 578, 580. 

Bina Selenides. Most biaary selenides are formed by beating selenium ia the presence of the element, reduction of selenites or selenates with carbon or hydrogen, and double decomposition of heavy-metal salts ia aqueous solution or suspension with a soluble selenide salt, eg, Na2Se or (NH 2S [66455-76-3]. Atmospheric oxygen oxidizes the selenides more rapidly than the corresponding sulfides and more slowly than the teUurides. Selenides of the alkah, alkaline-earth metals, and lanthanum elements are water soluble and readily hydrolyzed. Heavy-metal selenides are iasoluble ia water. Polyselenides form when selenium reacts with alkah metals dissolved ia hquid ammonia. Metal (M) hydrogen selenides of the M HSe type are known. Some heavy-metal selenides show important and useful electric, photoelectric, photo-optical, and semiconductor properties. Ferroselenium and nickel selenide are made by sintering a mixture of selenium and metal powder. 

There are few reports on nickel(II) coordinated to sulfate and selenate species.1688... 

Na2H20O14Se sodium selenate decahydrate 10102-23-5 25.00 1.6100 1 3172 Ni2P nickel phosphide 12035-64-2 25.00 7.3300 1... 

As for their stable analogs, the adsorption of radionuclides may depend on experimental conditions. Any variation results from the chemistry of the element, not form its radioactive nature. For example, the adsorption of the alkali metal cesium is largely independent of pH, whereas pH dependence is to be expected for oxyanions (Chapter 5, this volume) such as selenite and selenate and for transition metals such as nickel, silver, and palladium. 

EXPLOSION and FIRE CONCERNS combustible solid NFPA rating (NA) reacts to form explosive products with metal amides contact with acids may cause formation of poisonous hydrogen selenide gas incompatible or reacts violently with barium carbide, bromine pen-tafluoride, chromic oxide, fluorine, lithium carbide, lithium silicon, metals, nickel, sodium, nitric acid, nitrogen trichloride, oxygen, potassium, potassium bromate, rubidium carbide, zinc, silver bromate, uranium, strontium carbide, and thorium carbide toxic gases and vapors may be released in a fire involving selenium, sodium selenite, sodium selenate, and selenium dioxide use water for firefighting purposes. 

The corrosion protection is increased if a crack-free chromium layer or a chromium layer with microcracks is added to the copper/nickel or to the nickel or double nickel layer. A crack-free chromixun film is possible if special additives are added to the chromium-plating electrolyte. Manganese salts, selenic acid, and indium sulfate are mentioned in the literature. The film also has to be sufficiently thick (>22 pm). The stabiKty of the film is not very high because crack formation is a permanent process in these films. 

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