Thorium chromate

Thorium Chromate, Th(Cr04)2.3H20, has been prepared. ... 

Numerous patents6 have been issued for the use of thorium chromate, thorium tungstate, and other salts in the preparation of magnesium flashlight powders. It is claimed that such powders evolve les,s smoke than those which consist of magnesium alone. 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

Laurone has been prepared by hydrating and decarboxylating decylketene dimer.3 It has also been prepared by distilling calcium laurate 4 by heating lauric acid with phosphorus pent-oxide 5 by heating barium laurate under reduced pressure 6 by the ester condensation of ethyl laurate with sodium ethoxide 7 or of methyl laurate with sodium hydride 8 followed by ketonic hydrolysis by catalytic ketonization of lauric acid over a chromate catalyst 9 or by passing lauric acid over thorium dioxide at 400°.10... 

For detailed explanations of the chemistry of specific prreipitation titrations the reader is referred to other sources. These include methods such as the Mohr method for halides using the silver chromate end point, the Fajans adsorption indicator method, the Volhard method for FeSCN end point, the titration of halide mixtures with the attendant solid-solution and adsorption effects, the titration of fluoride with thorium(IV), and the titration of sulfate with barium ion. 

Separation. — The separation of thorium from the rare earth metals with which it is still mixed may be accomplished by three methods (1) the carbonate separation depends on the fact that thorium carbonate is much more soluble in sodium carbonate than the carbonates of the rare earth metals (2) by the fractional crystallization of the mixed sulfates at 15°-20°, crystals of Th(S04)2 8 H20 are obtained at the insoluble end of the series (3) thorium oxalate forms a soluble double salt with ammonium oxalate, while the rare earth oxalates are almost insoluble in this reagent. Some other methods which have been suggested are fractionation of the chromates,4 of the hydrogen alkyl sulfates,5 of the acetates, by the use of sebacic add 6 and hydrogen peroxide. 

In this two-parameter approximation three different models were tested, k = kff, k = k(filf and k = kjf/n. Hietanen found that the experimental data could be described equally well by these models with ko between 0.5 to 1.0 for the first two models and about 0.1 for the third. The value of logio for the three models were - 7.50, - 7.65 and -9.15, respectively. The core-and-link model is related to chain stractures found in solid state for so called basic salts , thorium hydroxide sulphate and thorium hydroxide chromate ([1949SIL/LUN], [1950LUN]). However, in solution systems, a model with a very large number of complexes does not make chemical sense and the model was also abandoned in later studies. 

The results are plotted in Fig. 54. The compound thorium chromatobis-chromate, Th(Cr04)2.Cr03.3H20, is better represented by this formula than by... 

Sigmon GE, Bums PC (2010) Crystal chemistry of thorium nitrates and chromates. J Solid State Chem 183 1604-1608... 

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