Ammonium acid formate chromates

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 one-bath chroming method (metachrome process), complex formation must be preceded by dye diffusion. For this reason, the release of CrVI must be delayed. The dye liquor is prepared with metachrome mordant (a mixture of sodium chromate and ammonium sulfate) and sodium sulfate. After a prerun at 40-50 °C, the system is heated slowly and dyed at boiling temperature for 45-90 min. Shortly before dyeing is completed, the bath is exhausted by the addition of acetic acid. 

The raw material for this preparation is the chromic anhydride from the preceding preparation, which contains at least a small amount of sodium acid sulphate. This dissolves with the chromic anhydride, and it should remain in the mother liquor (as neutral sulphate) from which the ammonium chromate is crystallized. The second and third crop of crystals of the latter, however, are likely to be contaminated with sodium sulphate. An excess of ammonium hydroxide is used to insure the formation of the neutral chromate. 

From what has been said about the influence of the cations it follows that the highest current efficiency is obtained when electrolysis is carried out with a neutral solution of ammonium sulphate. With such a solution the formation of harmful Caro s acid is almost entirely avoided. Another advantage of a neutral solution is that no diaphragm is needed to prevent the reduction of persulphate at the cathode. The addition of a small amount of alkali chromate to the solution will suppress reduction as a thin film of chromium hydroxide is formed on the cathode surface which prevents the persulphate ions coming into contact with the electrode. 

One of the simplest methods of preparation is by decomposition of a thermally unstable compound. The nitrate or chloride is often preferred, sulphates tend to decompose at higher temperatures. Where the presence of residual traces of anion is to be avoided, the metal salts of organic acids are particularly useful. Formates, oxalates, acetates etc, decompose at low temperatures and often reduce the metal at the same time. For the preparation of catalysts from anions, the ammonium salt is frequently used. Metallic salts of complex acids can be used as a source of metal oxide mixtures. Decomposition of the appropriate chromate, tungstate, molybdate or vanadate will produce the mixed oxide. 

A common feature of the decompositions of many ammonium compounds is the identification of the first step in reaction as proton transfer. The consequent accumulation of protons with the residual oxy-anions may be followed by the elimination of water, accompanied by condensation (or continued condensation) of the anions, see chromates and phosphates above, ultimately leading to residual oxide formation. Alternatively the acid may be volatilized, many ammonium salts sublime... 

AMMONIUM NITRATE (6484-52-2) A strong oxidizer. An ingredient in dynamite. Violent reaction and/or the formation of explosive mixtures with hot water, reducing agents, combustible materials, organic materials, ammonium dichromate, barium chloride, barium nitrate, charcoal, cyanoguanidine, phosphorus, potassium chromate, potassium dichromate, potassium nitrate, potassium permanganate, sodium chloride, finely divided metals. Forms explosive or heat- and shock-sensitive compounds with acetic acid, alkali metals (potassium, sodium, etc.), ammonia, nitric acid, sodium hypochlorite, sulfur, urea. At elevated temperatures, contained or confined material may explode violently. 

In Scheme 1, the reactive species of Cr(VI) and paracetamol readily form chromate ester as the first step in the reduction of Cr(VI) [14]. Chromate ester undergoes oxidative decomposition in the next step (rate determining), leading to the formation of an intermediate and Cr(IV) [15]. The proposed mechanism is further supported by analysis of the products. Ammonia has been detected as ammonium ions in aqueous solution. Benzoquinone and acetic acid were also detected by the spot tests [16]. 

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