Solid nickel iodate compounds

Pracht et al. [97PRA/LAN] have summarised and examined phase relationships in the Ni(I03)2-H20 system. They concluded that, as reported in earlier papers [73COR], [73NAS/SHI], two tetrahydrates, a dihydrate and a higher hydrate, perhaps a decahy- 

15 K) (see Appendix A). This agreement is rather surprising as neither worker reported a measurement at 298.15 K, and there are doubts concerning whether equilibrium was attained, especially in the work of Cordfunke [73COR]. 

Fedorov et al. [73FED/SHM] measured the solubility of a solid with the reported composition of a trihydrate, Ni(103)2-3H20, in aqueous lithium perchlo-rate/nitrate mixtures at 298.15 K and ionic strengths from 0.5 to 4.0 M. Their solubility results near 25°C, on extrapolation to I =0, are similar to those from the other two studies. Based on the values obtained from experiments using solutions without nitrate, a value of the solubility product of Ni(I03)2 3H20, log,o K° = - (5.09 0.16) is calculated (see Appendix A). 

It is clear from all the studies that the kinetics of the interconversion of the hydrates is slow at room temperature. The evidence for a true trihydrate is slim, yet might be the result of catalysed precipitation of a more stable form that is difficult to synthesize in other media. It might also reflect insufficient periods of equilibration, or that the solid was not properly handled prior to analysis. There does not seem to be any thermodynamic information (vapoiu pressure measurements) available on the interconversion of the hydrates. 

In the present review the solubilities of Fedorov et al. [73FED/SHM] are assumed to relate to the dihydrate rather than the trihydrate . The three values for the dihydrate at 298.15 K are then in marginal agreement within the statistical (2ct) uncertainties. The average from the three studies is selected  

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BENSULFOID (7704-34-9) Combustible solid (flash point 405°F/207°C). Finely divided dry materia forms explosive mixture with air. The vapor reacts violently with lithium carbide. Reacts violently with many substances, including strong oxidizers, aluminum powders, boron, bromine pentafluoride, bromine trifluoride, calcium hypochlorite, carbides, cesium, chlorates, chlorine dioxide, chlorine trifluoride, chromic acid, chromyl chloride, dichlorine oxide, diethylzinc, fluorine, halogen compounds, hexalithium disilicide, lampblack, lead chlorite, lead dioxide, lithium, powdered nickel, nickel catalysis, red phosphorus, phosphorus trioxide, potassium, potassium chlorite, potassium iodate, potassium peroxoferrate, rubidium acetylide, ruthenium tetraoxide, sodium, sodium chlorite, sodium peroxide, tin, uranium, zinc, zinc(II) nitrate, hexahydrate. Forms heat-, friction-, impact-, and shock-sensitive explosive or pyrophoric mixtures with ammonia, ammonium nitrate, barium bromate, bromates, calcium carbide, charcoal, hydrocarbons, iodates, iodine pentafluoride, iodine penloxide, iron, lead chromate, mercurous oxide, mercury nitrate, mercury oxide, nitryl fluoride, nitrogen dioxide, inorganic perchlorates, potassium bromate, potassium nitride, potassium perchlorate, silver nitrate, sodium hydride, sulfur dichloride. Incompatible with barium carbide, calcium, calcium carbide, calcium phosphide, chromates, chromic acid, chromic... 

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