Cobalt blue nitrate

Modras (51) reported spot test reactions to differentiate hydralazine from closely related drugs. Reagents used were aqueous copper (I) chloride, aqueous ammonium molybdate, iodine in potassium iodide solution, aqueous cobalt (II) nitrate, alcoholic ninhydrin, and alcoholic bromophenol blue. The tests were performed on paper or on Silica Gel G. 

A powder which burns with a green flame is obtained by the addition of nitrate of baryta to chlorate of potash, nitrate of potash, acetate of copper. A white flame is made by the addition of sulfide of antimony, sulfide of arsenic, camphor. Red by the mixture of lampblack, coal, bone ash, mineral oxide of iron, nitrate of strontia, pumice stone, mica, oxide of cobalt. Blue with ivory, bismuth, alum, zinc, copper sulfate purified of its sea water [sic]. Yellow by amber, carbonate of soda, sulfate of soda, cinnabar. It is necessary in order to make the colors come out well to animate the combustion by adding chlorate of potash.15... 

Ammonium tetrathiocyanatomercurate(II)-cobalt sulphate test This test is similar to that described under reaction 8, except that a minute amount of a dilute solution of a cobalt salt (nitrate, sulphate or acetate) is added. Coprecipitation of the cobalt tetrathiocyanatomercurate(II) yields a blue precipitate composed of mixed crystals of Zn[Hg(SCN)4] + Co[Hg(SCN)4], Iron(II) salts give a red colouration but this can be eliminated by the addition of a little alkali fluoride (colourless [FeF6]3- ions are formed). Copper salts should be absent. 

A solution containing 0.22 g (2 mmoles) of mimt in 5 mL of a solution containing ethyl acetate and triethyl orthoformate (95.5% v/v) is added to a solution containing 0.29 g (1 mmole) of hydrated cobalt(U) nitrate (Co(N03)2-6H20) in 10 mL of the same solvent. The resultant mixture is then refluxed in a 50-mL, single-necked, round-bottomed flask for 30 minutes. The subsequent treatment of the deep-blue crystalline product is the same as in (a). Yield, 90% as Co(C4H6N2S)2(N03)2. 

When colorless hydrochloric acid Is added to a red solution of cobalt(ll) nitrate, the solution turns blue, a sign that a chemical reaction has taken place. 

This pigment is described by Riffault et al. (1874) as a combination of aluminium oxide and cobalt oxide. It is prepared by faking an alum solution and dissolving in it cobalt nitrate, sulfate or chloride. A pink-white precipitate is formed with sodium or potassium carbonate the product is then washed, dried and calcined in a crucible at high temperature. It would consequently appear to be a manufacturing variant of cobalt aluminium oxide (that is, cobalt blue ) and is also stated to be synonymous with Gahn s ultramarine qq.v.). 

The German author Rose (1916) also refers to Payen (1823), stating that he developed a method of producing cobalt blue q.v.) by evaporating a mixture of the solutions of ammonia alum and cobalt nitrate, then calcining the resulting mixture. 

Cobalt(ll) nitrate (Co(N03)2) is used in ceramic glazes and produces a blue color when the ceramic is fired. This compound exists as a hydrate whose composition is 37.1% water and 62.9% Co(N03)2 by mass. Write the molecular formula for this hydrate. 

The salts have been used for centuries to produce brilliant and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. It is the principal ingredient in Sevre s and Thenard s blue. A solution of the chloride is used as a sympathetic ink. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has been found effective in correcting a certain mineral deficiency disease in animals. 

That is, a mixture of 1-, 2-diaquo-tetrammino-cobaltic chloride and 1-, 2-diehloro-tetranimino-cobaltic chloride is formed. The aquo-salt is readily soluble in water but the diehloro-salt sparingly so. The last named forms intense blue crystals which are contaminated with small quantities of the praseo-salt, from which it may be freed by transforming it into the dithionate. The dithionate is practically insoluble, but the chloride may be regenerated from it by rubbing it with ammonium chloride. The bromide, the iodide, and the nitrate have all been prepared. 

Cobalt Tetrarsenite, Co3As409, is obtained as an amethyst-coloured powder by the interaction of solutions of potassium hydrogen di-arsenite and cobaltous nitrate.8 It dissolves in dilute hydrochloric and nitric acids also in caustic potash, in which it forms a blue solution which decomposes on heating. In aqueous ammonia it gives a brown solution, and in aqueous potassium cyanide a yellow one. 

Thirty grams of mercuric chloride and 44.5g of potassium thiocyanate are dissolved in 500ml of water and mixed with a solution of 20g of cobalt nitrate 6-hydrate in 50ml of water. A shower of small deep blue crystals of the difficultly soluble complex salt begins to form almost immediately. The mixture is allowed to stand for twelve hours to complete the predpitation and then suction-filtered. The product is washed with three 30ml portions of cold water, drained well, and then rinsed with two 25ml volumes of 95% alcohol to aid in drying. The material is dried in air or in the oven at 100° C. 

A mixture of 0.05 mole of a cobalt salt (14.5g of the nitrate or 12g of the chloride—both 6-hydrate) and 21g of potassium thiocyanate are heated in 30ml of water until solution is complete. The dark blue liquid is cooled in ice until crystallization of potassium nitrate or chloride is complete and then suction-filtered. The residue is washed repeatedly with 10ml portions of ethyl acetate until it is... 

E. P. Alvarez 2 found that the pemitrates react with soln. of lead acetate (white precipitate), silver nitrate (white precipitate), mercurous nitrate (white precipitate with rapid decomposition), mercuric chloride (red precipitate), copper sulphate (blue precipitate), zinc and cadmium sulphates (white precipitate), bismuth nitrate (white precipitate), gold chloride (slight effervescence and escape of oxygen), manganous chloride (pink precipitate), nickelous chloride or sulphate (greenish-white precipitate), cobaltous nitrate and chloride (pink precipitate), ferrous sulphate (green or bluish-green precipitate), ferric chloride (red ferric hydroxide), and alkaline earth chlorides (white precipitates). The precipitates are all per-salts of the bases in question. 

A common test for zinc and aluminium is to heat together before the blow-pipe the salt suspected to contain the metal with cobalt nitrate it is probable that the green colour produced by zinc is due to the formation of a cobalt zincate, Co(Zn02), and the blue colour shown by alumina to a similar body, Co(A102)2. 

The anhydrous salt may be obtained by maintaining for a prolonged period at 80° to 90° C. a mixed solution of cobalt nitrate and Alkali iodate in the presence of free nitric acid. It is also formed at ordinary temperatures by mixing saturated solutions of cobalt nitrate and alkali iodate and agitating with a glass rod the flocculent, rose-coloured, hydrated precipitate, when it yields the blue-violet anhydrous compound. The salt is also produced by heating the same solutions from two to three hours in a glass tube at 120° C. 

Cobaltic Nitrate.—When a concentrated solution of cobaltous nitrate is electrolysed in a divided cell, it assumes a deep indigo-blue colour, but soon returns to its original state when the current is stopped.6 Presumably the colour change is due to the formation in solution of an unstable cobaltic nitrate. 

Cobalt Arsenites.—When a dilute solution of cobalt nitrate is precipitated with sodium metarsenite, a violet-blue voluminous deposit of cobalt pyro-arsenite, Co2As205 or 2CoO.As203, is obtained.3... 

B. Add 5 mL of a 1 50 aqueous solution to 75 mg of cobalt nitrate and 300 mg of ammonium thiocyanate dissolved in 2 mL of water, mix, and then make the resulting solution acid with 2.7 N hydrochloric acid. A pale blue precipitate forms. 

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