Chromium solubility

Chloro 6-trichloromethyl pyridine (N-Serve ) Chromates, certain insoluble forms Chromic acid and chromates (as Cr) Chromium, soluble chromic and chromous salts (as Cr)... 

James B.R. Hexavalent chromium solubility and reduction in alkaline soils enriched with chromite ore processing residue. J Environ Qual 1994 23 227-233. 

Atomic absorption determination of chromium soluble in uranium hexafluoride 109-115... 

Contrary to cerium system, lanthanum modified support exhibits a limited chromium solubility, since a-Cr203 appears already at the deposition of 7% of Cr. At 1273 K, the content of a-Al203 is practically as large as in the cerium system with 2 and 7% of chromium and significantly lower, if Cr content is 15% (Fig. 1). 

At this level the conclusion was that the reaction between oxygen and chromium(ni) species resulted in a new chromium soluble species. 

UV-Visible absorption spectra of the molten electrolyte when oxygen was introduced gave information about the occurrence of a new chromium soluble species. The new absorption band which appears in the spectra was attributed to the Cr(VI) species, and the following reaction mechanism was assumed ... 

CHROMIUM SOLUBLE CHROMIC AND CHROMOUS SALTS (AS CR) Cr Synonyms vary depending upon spcciFic compound Water Properties vary dcpcmDng upon spcdfic compound ... 

Uranium, with magnesium additions up to 2000 ppm, does not affect the solubility of iron in bismuth. The possible effects on chromium solubility are not known at this time. 

Chromium has a marked effect on the solubility of iron, whereas the chromium solubility itself is not affected. An apparent solubility product is observed as is shown in Fig. 20-10 by the line titled "Apparent solubility product. Below 450°C, the iron solubility appears to be increased by saturating the solution with chromium. Above that temperature, the iron solubility is markedly reduced by chromium. 

Chromium(IH) chloride, chromic chloride, CrClj. Violet solid (Cr plus CI2, hydrate plus SOCI2) only soluble in water in presence of Cr. Forms many complexes including the hydrates [Cr(H20)6]Cl3 - violet, [Cr(H20)jCl]Cl2,H20 - green, [Cr(H20)4Cl2]Cl,2H20 - green. 

Chromium(VI) oxide is very soluble in water initially, chromic acid , H2Cr04, may be formed, but this has not been isolated. If it dissociates thus ... 

The chromates of the alkali metals and of magnesium and calcium are soluble in water the other chromates are insoluble. The chromate ion is yellow, but some insoluble chromates are red (for example silver chromate, Ag2Cr04). Chromates are often isomorph-ous with sulphates, which suggests that the chromate ion, CrO has a tetrahedral structure similar to that of the sulphate ion, SO4 Chromates may be prepared by oxidising chromium(III) salts the oxidation can be carried out by fusion with sodium peroxide, or by adding sodium peroxide to a solution of the chromium(IIl) salt. The use of sodium peroxide ensures an alkaline solution otherwise, under acid conditions, the chromate ion is converted into the orange-coloured dichromate ion ... 

Hydrated chromium Ill) nitrate is a dark green, very deliquescent solid, very soluble in water. The anhydrous nitrate is covalent. 

Addition of alkali gives a green gelatinous precipitate of chromium(III) hydroxide, soluble in a large excess of strong alkali. 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

Most catalysts for solution processes are either completely soluble or pseudo-homogeneous all their catalyst components are introduced into the reactor as Hquids but produce soHd catalysts when combined. The early Du Pont process employed a three-component catalyst consisting of titanium tetrachloride, vanadium oxytrichloride, and triisobutjlalurninum (80,81), whereas Dow used a mixture of titanium tetrachloride and triisobutylalurninum modified with ammonia (86,87). Because processes are intrinsically suitable for the use of soluble catalysts, they were the first to accommodate highly active metallocene catalysts. Other suitable catalyst systems include heterogeneous catalysts (such as chromium-based catalysts) as well as supported and unsupported Ziegler catalysts (88—90). 

Strong acids and strong alkaUes can severely bum the skin, chromium compounds can produce skin rashes, and repeated exposure to solvents causes removal of natural oils from the skin. Infection is always a concern for damaged skin. Absorption through the skin is possible for materials that are appreciably soluble iu both water and oil, eg, nitrobenzene, aniline, and tetraethyllead. Other materials can be absorbed if first dissolved iu extremely good solvents, eg, dimethyl sulfoxide. Subcutaneous iujection can occur accidentally by direct exposure of the circulatory system to a chemical by means of a cut or scratch or iuadvertent penetration of the skin with a hypodermic needle. 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

Brewers and bakers dried yeasts are used as dietary supplements. They contribute some protein and trace minerals, and some B vitamins, but no vitamin C, vitamin B 2 or fat-soluble vitamins. The glucose tolerance factor (GTE) of yeast, chromium nicotinate, mediates the effect of insulin. It seems to be important for older persons who caimot synthesize GTE from inorganic dietary chromium. The ceU wall fraction of bakers yeast reduces cholesterol levels in rats fed a hypercholesteremic diet. 

These siUca-supported catalysts demonstrate the close connections between catalysis in solutions and catalysis on surfaces, but they are not industrial catalysts. However, siUca is used as a support for chromium complexes, formed either from chromocene or chromium salts, that are industrial catalysts for polymerization of a-olefins (64,65). Supported chromium complex catalysts are used on an enormous scale in the manufacture of linear polyethylene in the Unipol and Phillips processes (see Olefin polymers). The exact stmctures of the surface species are still not known, but it is evident that there is a close analogy linking soluble and supported metal complex catalysts for olefin polymerization. 

The anhydrous halides, chromium (ITT) fluoride [7788-97-8], CrF, chromium (ITT) chloride [10025-73-7], CrCl, chromium (ITT) bromide [10031-25-1], CrBr, and chromium (ITT) iodide [13569-75-0], Crl, can be made by the reaction of Cr metal and the corresponding halogen at elevated temperatures (12,36). Other methods of synthesis for the haUdes are also possible (36—38). All of the haUdes have a layer stmcture and contain Cr(III) in an octahedral geometry. They are only slightly soluble in water but dissolve slowly when Cr(II) or a reducing agent such as Zn or Mg is added. 

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