Sodium chromate, anhydrous

Chemical Designations - Synonyms Neutral sodium chromate, anhydrous Sodium chromate (VI) Chemical Formula Na2Cr04. 

Sodium chromate, anhydrous, NajCr04. Mol. wt. 162.00. Supplier Fisher. 

Sodium Chromate Neutral Sodium Chromate, Anhydrous Sodium Chromate (Vi) ... 

Synonym Neatsfoot Oil Necatorina Nechexane Neutral Ahhonium Pluoride Neutral Anhydrous Calcium Hypochlorite Neutral Lead Acetate Neutral Nicotine Sulfate Neutral Potassium Chromate Neutral Sodium Chromatetanhydrous Neutral Verdigris Nickel Acetate Nickel Acetate Tetrahyorate Nickel Ammonium Sulfate Nickel Ammonium Sulfate Hexahydrate Nickel Bromide Nickel Bromide Trihydrate Nickel Carbonyl Nickel Chloride Nickel Chloride Nickel Cyanide Nickel Iiu Fluoborate Nickel Fluoroborate Solution Nickel Fluoroborate Nickel Formate Nickel Formate Dihyorate Nickel Nitrate Nickel Nitrate Hexahydrate Nickel Sulfate Nickel Tetracarbokyl Nickelous Acetate Nickelous Sulfate Nicotine Nicotine Sulfate Nifos Nitralin Nitram O-Nitraniline P-Nitraniline Nitric Acid Nitric Acid, Aluminum Salt Nitric Acid, Iron (111) Salt Compound Name Oil Neatsfoot Carbon Tetrachloride Neohexane Ammonium Fluoride Calcium Hypochlorite Lead Acetate Nicotine Sulfate Potassium Chromate Sodium Chromate Copper Acetate Nickel Acetate Nickel Acetate Nickel Ammonium Sulfate Nickel Ammonium Sulfate Nickel Bromide Nickel Bromide Nickel Carbonyl Nickel Chloride Nickel Chloride Nickel Cyanide Nickel Fluoroborate Nickel Fluoroborate Nickel Fluoroborate Nickel Formate Nickel Formate Nickel Nitrate Nickel Nitrate Nickel Sulfate Nickel Carbonyl Nickel Acetate Nickel Sulfate Nicotine Nicotine Sulfate Tetraethyl Pyrophosphate Nitralin Ammonium Nitrate 2-Nitroaniline 4-Nitroaniline Nitric Acid Aluminum Nitrate Ferric Nitrate... 

In the process (Fig. 1), the ore is ground and mixed with ground limestone and soda ash, and roasted at approximately 1200°C in an oxidizing atmosphere. The sintered mass is crushed and leached with hot water to separate the soluble sodium chromate. The solution is treated with sulfuric acid to convert the sodium chromate to sodium dichromate plus sodium sulfate. Some of the sodium sulfate crystallizes in the anhydrous state from the hot solution during acidification as well as in the evaporators during concentration of the dichromate solution. From the evaporator, the hot, sat-... 

In the manufacture of sodium dichromate, byproduct Na2S04 crystallizes directly as the anhydrous material when H2S04 is added to a boiling solution of sodium chromate ... 

For example, oxidation of 4-oclyne (0.015 mole) with C1O3 -Pyj (0.225 mole) in methylene chloride at room temperature for 24 hr. (N2) gives 4-octyne-3-onc in 42% yield. Anhydrous sodium chromate (Na2Cr04) can also be used, but yields are lower. Considerable amounts of starting alkyne are recovered. ... 

Sodium chromate may be obtained anhydrous, and in the form of a deea-, hexa-, and tetra-hydrate, according to the conditions of crystallisation. The anhydrous salt, Na2Cr04, separates from its solution on evaporation at a temperature above 62-8° C. It forms yellow crystals in the rhombic system (bipyramidal) ... 

Chromate ion may be detected and detd using the methods listed under Chromates, Analytical Procedures, Sodium ion may be detected and detd using the methods described in Refs 1,2 3 US Federal requirements for Na chromate, anhydrous, technical grade and tests are described in Ref 4... 

J. W. tgers said that the anhydrous sodium chromate forms yellow, columnar... 

F. T. Frerichs observed no precipitation and F. Kuhlmann found that calcium carbonate is only partially converted into the chromate by a soln. of potassium chromate hme-water gives no precipitate with a soln. of potassium chromate. F. Mylius and J. von Wrochem obtained the anhydrous chromate by heating the hydrated salt—G. N. Wyroubofi said at 300°—or by warming a supersaturated soln., containing 15 to 20 per cent. CaCr04, over 36°. The yellow powder consists of fine needles. L. Bourgeois obtained crystals of the anhydrous chromate by melting a mixture of 2 eq. of calcium chloride with an eq. each of potassium and sodium chromates. D. Vorlander and H. Hempel observed no transformation into... 

I. Stsherbakoff studied the electrolysis of soln. of sodium chromate using a mercury cathode. T. W. Richards and G. L. Kelley found that sodium dichromate can be readily purified from potassium salts and sulphates by recrystallization from water a number of times. The "zHaCl conditions of equilibrium, worked out by F. A. H. Schreinemakers, are illustrated by Fig. 34. F. Mylius and R. Funk gave 83° for the transition temp, from the dihydrate to the anhydrous salt. The solubility, S per cent., of sodium dichromate in water is ... 

Pigment yellow 152 Pigment yellow 154 Quinizarin Silica, fumed Sodium chromate Sodium molybdate anhydrous Sodium molybdate dihydrate Sodium polyacrylate Talc Ultramarine blue... 

Glyceraldehyde Glycolic acid Glyoxal Melamine Methylcellulose Oxalic acid dihydrate Sodium acetate anhydrous Sodium bisulfide Sodium chlorate Sodium chromate Sodium chromate tetrahydrate Sodium polymetaphosphate tanning, soft leather Glutaral... 

The roasted clinker is then leached out with hot water and the resulting liquor filtered to remove insoluble silica, along with aluminum and iron oxides present as impurities in the original chromite ore. Pure sodium dichromate is then crystallized and dried. The anhydrous sodium chromate can then be reduced to chromium trioxide by simple carbothermic reduction. Note that the sodium chromate produced can be converted into the dichromate by dissolving it in sulfuric acid and is the basis for the manufacture of all industrially important chromium chemicals. Once produced, chromium trioxide is mixed with aluminum powder and lime and placed inside a refractory-lined steel vessel. The exothermic reaction is started by igniting a pyrotechnic mixture made of barium peroxide and aluminum powder or potassium chlorate aluminum powder ... 

When sodium chloride is fused with anhydrous chromium(II) chloride the product is NaCrCI5 regardless of the proportions of chlorides used.222 Other cations give tetra- or tri-chloro-chromates(II) as in Sections 35.3.7.3.ii and 35.3.7.3.vi above. The solvate [pyH]3[CrBr5]-2MeC02H has been isolated from the metal acetate and pyridine in a mixture of acetyl bromide and acetic acid, and there is considerable splitting of the spin-allowed d-d band in the reflectance spectrum of this complex,255 but no detailed investigations of pentahalochromates have been reported. 

Anhydrous calcium chromate may be conveniently prepared by dehydration of any of the above hydrates at high temperatures. It is less soluble than the hydrates, and is the most stable form. It dissolves in molten sodium nitrate. ... 

A solution of 1.58 g (5.68 mmol) of tetrabutylammonium chloride in 28 mL of water is added rapidly with stirring to a solution of 0.54 g (5.4 mmol) of chromium trioxide in 14 mL of water at room temperature. The tetrabutylammonium chromate is extracted with 200 mL of chloroform. The chloroform solution is concentrated to 6 mL, and a solution of 0.5 g (2.71 mmol) of benzhydrol in 4 mL of chloroform is added with stirring. After 3 h at 60 °C, the mixture is diluted with ether, and the solution is poured into 1 N sodium hydroxide. The ether layer is washed with a saturated solution of sodium chloride, dried with anhydrous sodium sulfate, and evaporated to give 0.450 g (91%) of benzophenone, mp 45-47 °C. 

PHYSICAL PROPERTIES Physical properties of chromic acid and specific chromates are provided for illustrative purposes, (chromic acid) dark-red, rhombic crystals or powder deliquescent (i.e., able to absorb atmospheric water vapor and become liquid) odorless true chromic acid, sulfuric acid, exists only in solution very soluble in water, soluble in sulfuric acid and most organic solvents MP (197.2°C, 387°F) BP (250°C, 482°F)(decomposes) DN (2.70 g/cm at 20°C) SG (2.70) VD (NA) VP (very low) (potassium chromate) lemon-yellow, rhombic crystals odorless solid soluble in water insoluble in alcohol, acetone, and cyanogen MP (975°C, 1787°F) BP (data not available) DN (2.73 g/cm at 18°C) SG (2.7 at 20°C) VD (NA) VP (approximately 0 mmHg at 20°C) (sodium dichromate) reddish to bright orange crystals odorless solid somewhat deliquescent anhydrous very soluble in water insoluble in alcohol MP (357°C, 674.6°F) BP (400°C, 752°F) (decomposes) DN (2.348 g/cm at 25°C) SG (2.34) VD (NA) VP (approximately 0 mmHg at 20°C). 

This stated that compounds which crystallise in the same form (i.e. are isomorphous) are similar in atomic composition, and he quoted as examples the sodium phosphates and arsenates, in which an arsenic atom takes the place of a phosphorus atom. Mitscherlich used the fact that potassium selenate was isomorphous with potassium sulphate to deduce the formula of potassium selenate, and hence determine the atomic weight of selenium. Berzelius used the isomorphism of the sulphates and the chromates as evidence that the formula of anhydrous chromic acid was CrOj. He suggested that the lower oxide of chromium had a formula of Q2O3, and since this was isomorphous with the oxides of iron and aluminium, he was able to propose correct formulae for these compounds. 

Neutral Ahhonium Pluoride Neutral Anhydrous Calcium Hypochlcrite Neutral Lead Acetate Neutral Nicotine Sulfate Neutral Potassium Chromate Neutral Sodium Chromatetanhydrous Neutral Verdigris Nickel Acetate... 

The infrared spectra of sodium scandium chromates are similar to those of other Sc ternary compounds. The spectrum for the anhydrous phase is very simple, suggesting high structural symmetry (cf. table 26). 

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