Ammonium carbonate molybdate solution

The reaction velocity is comparatively slow, but increases with increasing concentration of acid. The addition of three drops of a neutral 20 per cent ammonium molybdate solution renders the reaction almost instantaneous, but as it also accelerates the atmospheric oxidation of the hydriodic acid, the titration is best conducted in an inert atmosphere (nitrogen or carbon dioxide). 

Better results are obtained by transferring 25.0 mL of the diluted hydrogen peroxide solution to a conical flask, and adding 100 mL 1M(1 20) sulphuric acid. Pass a slow stream of carbon dioxide or nitrogen through the flask, add 10 mL of 10 per cent potassium iodide solution, followed by three drops of 3 per cent ammonium molybdate solution. Titrate the liberated iodine immediately with standard 0.1M sodium thiosulphate in the usual way. 

Synonym Ammonia Water Amfbnioformaldehyde Ammonium Acetate Ammonium Acid Fluoride Ammonium Amidosulfonate Ammonium Amidosulphate Ammonium Benzoate Ammonium Bicarbonate Ammonium Bichromate Ammonium Bifluoride Ammonium Carbonate Ammonium Chloride Ammonium Citrate Ammonium Citrate, Dibasic Ammonium Decaborate Octahydrate Ammonium Dichromate Ammonium Disulfate-Nickelate (II) Ammonium Ferric Citrate Ammonium Ferric Oxalate Trihydrate Ammonium Ferrous Sulfate Ammonium Fluoride Ammonium Fluosilicate Ammonium Formate Ammonium Gluconate Ammonium Hydrogen Carbonate Ammonium Hydrogen Fluoride Ammonium Hydrogen Sulfide Solution Ammonium Hydroxide Ammonium Hypo Ammonium Hyposulfite Ammonium Iodide Ammonium Iron Sulfate Ammonium Lactate Ammonium Lactate Syrup Ammonium Lauryl Sulfate Ammonium Molybdate Ammonium Muriate Ammonium Nickel Sulfate Ammonium Nitrate Ammonium Nitrate-Urea Solution Ammonium Oleate... 

In a 25-ml standard flask place 5 ml of a 1 1 mixture of ammonium molybdate solution and 1 M sulphuric acid, and add 3 ml of acetone and an aliquot of sample solution e.g., neutralized solution from sodium carbonate fusion) containing not more than 0.2 mg of Si. Dilute to the mark with water, mix well, let stand for 15 min, and measure the absorbance at... 

A little of the powdered mineral is decomposed by fusion with sodium-potassium carbonate in a loop of platinum wire the silicic acid is thus brought into a reactive form. The bead is dissolved (micro crucible) in a drop oil N nitric acid. Ammonium molybdate solution is added and the rest of the procedure is as described on page 418. Phosphates must be absent. 

Procedure. A little of the solid is mixed in a small platinum crucible with a few milligrams of calcium fluoride. Two drops concentrated sulfuric acid are added and the crucible covered with a piece of filter paper on which is placed a drop of ammonium molybdate solution. The crucible is heated over a microburner for about 1 minute and allowed to cool for 3-5 minutes. The ammonium molybdate fleck is then treated with a drop of benzidine and developed over ammonia. Rocks containing carbonate and sulfide should be ignited before the test to prevent frothing (evolution of carbon dioxide) or reduction of the molybdate by hydrogen sulfide. 

Aluminum chloride, 26% Aluminum hydroxide Aluminum nitride Ammonia, dry vapor Ammonium acetate solution Ammonium bisulfate Ammonium bromide Ammonium carbonate Ammonium chloride, 10% Ammonium dichloride Ammonium hydroxide Ammonium hydroxide vapor Ammonium molybdate Ammonium nitrate Argon... 

Aminoethanol 2-Aminoisobutyric Acid Ammonia Ammonia Solution Ammonium Ammonium Acetate Ammonium Alum Ammonium Bicarbonate Ammonium Bichromate Ammonium Bifluoride Ammonium Bromide Ammonium Carbonate Ammonium Chloride Ammonium Dichromate Ammonium Fluoride Ammonium Glycolate Ammonium Hydrogen Carbonate Ammonium Hydrogen Fluoride Ammonium Hydrosulfide Ammonium Hydroxide Ammonium Hyposulfite Ammonium Iron Sulfate Ammonium Molybdate Ammonium m-Phosphate Ammonium Nitrate Ammonium o-Phosphate Ammonium Oxalate Ammonium Peroxydisulfate Ammonium Persulfate Ammonium Phosphate Ammonium Phosphate Dibasic Ammonium Rhodanide Ammonium Sulfamate Ammonium Sulfate Ammonium Sulfide Ammonium Thiocyanate Ammonium Thioglycolate Ammonium Thiosulfate... 

Phosphates. — To the solution of 20 gm. of sodium carbonate in 50 cc. of nitric acid add 50 cc. of a solution of ammonium molybdate in nitric acid. No yellow precipitate should form in the liquid on standing two to three hours at about 40° C. 

When a quantitative determination of the phosphoric acid and chlorine is required, a fresh quantity of ash is prepared from a weighed amount of the meat sample mixed with an alkali such as milk of lime, sodium carbonate, etc. The phosphoric acid and the chlorine are determined in the nitric acid solution of the ash, the former by the ammonium molybdate method, and the latter either volumetrically or gravimetrically as silver chloride. 

Preparation.—Although the purest molybdenum is obtained from wulfenite, the chief commercial source is molybdenite, which is converted into the trioxide by roasting in air either with or without the addition of sand, and, on dissolving the residue in ammonia, a solution of ammonium molybdate is obtained. This salt, freed from copper by treatment in ammoniacal solution with ammonium sulphide, and from aluminium by the addition of potassium carbonate, on ignition yields molybdenum dioxide alternatively, heating with excess of sulphur yields pure molybdenum disulphide, MoS, which on roasting, or by treatment with nitric acid, is converted into the trioxide MoOj. ... 

The blue oxide is best obtained by allowing powdered molybdenum to remain for a long time at ordinary temperatures in contact with an aqueous suspension of the trioxide, filtering, and then digesting with a further quantity of molybdenum. The solution is evaporated in vacuo. Cold water used for washing the solid should previously be rendered air-free. Another good method of preparation consists in precipitating in the cold, by means of excess of a solution of hydrated molybdenum tetrachloride, a solution of ammonium molybdate in hydrochloric acid the precipitate is w ashed with air-free w ater in an atmosphere of carbon dioxide, and is dried m vacuo. 

Silicones are produced in the form of resins, oils, greases, and also as rubberlike elastic products. These materials also appear as processing aids in the manufacturing of plastics, as impregnation compounds, coatings, separating materials, mold releases, etc. They can be identified because they contain the element silicon. To test for silicon, mix approximately 30 mg of the sample with 100 mg sodium carbonate and 10 mg sodium peroxide. Heat this in a platinum or nickel crucible over a flame. Dissolve the melt in a few drops of water, boil it, and then add dilute nitric acid until the solution is neutral or slightly acidic. The identification of silicon then follows in the usual way with the addition of a few drops of ammonium molybdate. (See Chapter 4.)... 

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