Chromium sulfate, 6-hydrate

CCRIS 6186 Chromic sulfate Chromium sulfate hydrate Santotan KR. Peach-colored solid, occurring as several hydrated forms. Used in leather tanning. Solid d = 3.012 MLD (mus Iv)b247 mg/kg. 

The preparation of salts containing the [Cr(en)3]3+ cation from anhydrous chromium sulfate has been described previously in Inorganic Syntheses,1 and the merits of this, and other, methods have been reviewed.9 A more rapid route to this cation involves refluxing CrCl3 6H20 in methanol with ethylenediamine and zinc metal, which allows the substitution to proceed by way of the kineti-cally labile chromium(II) species.10 All of these preparations yield hydrated salts the procedure described below leads to anhydrous [Cr(en)3] Br3. 

The Cr1 ion readily forms complexes it exists in aqueous solution as CrfH 0)j. and forms other complexes wilh anions, such asCr(H 0).CI , Crother properties due to variation in the bonding. Compounds or the trichloride have been reported with the following arrangements CrtHjOlsClj. [CrfHiOlsCljCIi- HiO. and [Cr(HiO)4Cf CU2 H 0 Trivalenl chromium also forms double salts, notably the chromium alums, hydrated double salts of Cr(III) sulfate and the alkali metal (or thallium or ammonium) sulfates. 

Five grams (0.0135 mol) of tris(biguanido) chromium (III) 1-hydrate is dissolved in 200 ml. of water and treated with a solution of 5,7 g. (0.043 mol) of ammonium sulfate in 10 ml. of water. The sparingly soluble tris(biguanide)-chromium sulfate is precipitated with liberation of ammonia. The mixture is heated on the water bath, whereby... 

Chromium wastes are commonly treated in a two-stage batch process. The primary stage is used to reduce the highly toxic hexavalent chromium to the less toxic trivalent chromium. There are several ways to reduce the hexavalent chrome to trivalent chrome including the use of sulfur dioxide, bisulfite, or ferrous sulfate. The trivalent chrome is then removed by hydroxide precipitation. Most processes use caustic soda (NaOH) to precipitate chromium hydroxide. Hydrated lime [Ca(OH)2] may also be used. The chemistry of the reactions is described as follows ... 

There are old reports of tris sulfate complexes " and a number of chromium(lll) sulfate hydrates are known. In recent years monosulfatopentaaquachromium(III) complexes have been prepared and characterized by IR spectroscopy sulfate probably behaves as a monodentate ligand. The basic chromium(III) sulfate Cr(0H)S04 H20 crystallizes in the non-centrosymmetric, monoclinic, space group O. Each chromium atom is coordinated octahedrally by two hydroxo groups, three sulfate O atoms and a water molecule. The metal atoms are joined by single hydroxo bridges forming an infinite chain. 

A solution of 26.8 g. of green chromium chloride hydrate [CrCl3(1130)4] Cl 2 H3O in an equal amount of water Is allowed to stand for 24 hours at room temperature, and a mixture of 10 g. of cone. H3SO4 and 4 g. of water is then added. The sulfate soon separates in bright green tablets. 

Synonyms Chromic sulfate Chromic sulfate hydrate Chromium sulfate Chromium sulfate (2 3) Chromium (III) sulfate Chromium (III) sulfate (2 3) Chromium (III) sulfate hydrate Cl 77305 Dichromium sulfate Dichromium trisulfate Sulfuric acid, chromium (3+) salt (3 2)... 

Tertiary and quaternary oxides (Al + Co, Sn Cu, Fe) chromium aluminium cobalt oxide chromium iron oxide ((Fe,Cr)203) chromium copper iron oxide (Cu0.Cr203.Fc203). Phosphates chromium phosphate hydrate (CrP04jcH20). Sulfates chromium sulfate (Cr2[S04]3) chromiimi sulfate hydrate (Cr2[S04]3.15H20 and Cr2[S04]3.18H20). 

Ghromium(II) Compounds. The Cr(II) salts of nonoxidizing mineral acids are prepared by the dissolution of pure electrolytic chromium metal ia a deoxygenated solution of the acid. It is also possible to prepare the simple hydrated salts by reduction of oxygen-free, aqueous Cr(III) solutions using Zn or Zn amalgam, or electrolyticaHy (2,7,12). These methods yield a solution of the blue Cr(H2 0)g cation. The isolated salts are hydrates that are isomorphous with and compounds. Examples are chromous sulfate heptahydrate [7789-05-17, CrSO 7H20, chromous chloride hexahydrate... 

A 500-ml three-necked flask fitted with a mechanical stirrer and a nitrogen inlet and outlet is charged with 30 g (approx. 0.055 mole) of hydrated chromium (III) sulfate, 200 ml of distilled water, 7.5 g (0.12 g-atom) of mossy zinc, and 0.4 ml (5.4 g, 0.03 g-atom) of mercury. The flask is flushed with nitrogen for 30 minutes and a nitrogen atmosphere is maintained. The mixture is then heated to about 80° with stirring for 30 minutes to initiate reaction. Then the mixture is stirred at room temperature for an additional 30 hours, by which time the green mixture has been converted to a clear blue solution. Solutions prepared as above are about 0.55 M in chromium (II) and are indefinitely stable if protected from oxygen. 

Chromate conversion coatings for aluminum are carried out in acidic solutions. These solutions usually contain one chromium salt, such as sodium chromate or chromic acid and a strong oxidizing agent such as hydrofluoric acid or nitric acid. The final film usually contains both products and reactants and water of hydration. Chromate films are formed by the chemical reaction of hexavalent chromium with a metal surface in the presence of accelerators such as cyanides, acetates, formates, sulfates, chlorides, fluorides, nitrates, phosphates, and sulfamates. 

Hydrated and anhydrous chromium(II) hydrazinium sulfates (N2H5)2Cr(S04)2 are known. They are air-stable, and in the latter (from isomorphism with the Zn11 complex) each metal ion is coordinated to the nitrogen atoms of two hydrazinium ions and four 6 atoms of bridging sulfato anions.135... 

Twenty grams of chromium nitrate 9-hydrate, or 0.05 moles of the hydrated sulfate or chloride, are fused with 30g of potassium thiocyanate as in (I), and the melt allowed to cool in a desiccator and then triturated with 25ml portions of ethyl acetate until no more material dissolves. The violet liquid is filtered a small green residue remains behind together with the potassium nitrate, sulfate, or chloride. The ethyl acetate extract is evaporated to dryness on the steam bath and the violet residue is further dried in vacuo. The anhydrous salt is violet. 

Commercial hydrated chromium (III) sulfate is dehydrated in an oven at 100-120°C. When the salt no longer dissolves in water the process is complete. ... 

Figure 8.20 Hydrate crystals (left to right) cobalt nitrate, calcium nitrate and nickel sulfate (top) and manganese sulfate, copper sulfate and chromium potassium sulfate (bottom).

Crude material prepared in glass on 3 g mol scale was distilled uneventfully at 40°C/ 0.067 mbar from a bath at 70—80°C. A 30 mol batch prepared in a glass-lined vessel with a stainless steel thermo-probe (and later found to contain 15 ppm of iron) decomposed very violently during distillation at 75°C/13 mbar from a bath at 130°C. Thermal analysis showed that the stability of the methyl (and ethyl) ester was very sensitive to traces of heavy metals (iron, copper, chromium, etc.) and was greatly reduced. Addition of traces of hydrated iron(II) sulfate led to explosive decomposition at 25°C. 

Tris (ethylenediamine) chromium-(III) iodide, 1-hydrate, 2 199 Tris (ethylenediamine) chromium-(III) sulfate, 2 198 Tris (ethylenediamine) chromium-(III) thiocyanate, 1-hydrate, 2 199... 

If tri8(ethylenediamine)chromium(III) chloride is prepared by the method of Rollinson and Bailar,7 it is worthy of note that if the dehydration of the hydrated chromium (III) sulfate is performed in a vacuum oven (2-3 mm. Hg, 70-80°C.) the anhydrous sulfate is obtained in a much more reactive form so that the reaction with ethylenediamine, when started by local heating, proceeds by itself and is finished within an hour. Editor s note For an alternative preparation, see Inorganic Syntheses, 10, 33 (1967) also ref. 26. 

A number of the intensely colored hydrated salts of trivalent chromium (the nitrate, sulfate, chloride, and the alum ) are doubtless familiar. The octahedral hexaaquochromium(III) ion, Cr(H20) 3, is violet, but aqueous solutions of chromic salts are often green as a result of replacement of water molecules in the complex by the anions present. The change of color occurring on heating a solution containing trivalent chromium and chloride ions should be recalled ... 

Trivalent chromium pigments include chromium oxide (Cr203) and hydrated chromium oxide (Cr203 xH20). Chromium oxide is prepared by calcination, either by reduction of sodium bichromate (Na2Cr207) with sulfur or carbon at 750-900°C or by reduction of sodium bichromate with ammonium chloride or ammonium sulfate at 700°C. Hydrated chromium oxide is manufactured by hydrolyzing a complex chromium borate, which in turn has been produced by heating sodium bichromate with boric acid in a furnace. 

Arsenic, barium, benzene, carbon tetrachloride, chromium, 1,2-dichloroethane, dichloromethane, ethylbenzene, toluene, trichloroethene Aluminium, antimony, arsenic, barium, boron, cadmium, chloral hydrate, chromium, copper, dichloroacetate, iron, mercury, zinc Ammonia, sulfate... 

A. Chromium(II) sulfate solution. A 3-1., thrcc-ncckcd flask fitted with a gaslight mechanical stirrer and nitrogen inlet and outlet stopcocks is chargeti with 3(K) g. at. 0..S5 mole) of hydrated... 

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydrate), 13548-43-1 (anhydrous)] M 478.4, m 94 loses 9H2O then dehydrates at 300°, df 1.72. Crystallise the double salt from a saturated... 

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