Silver metaphosphate

Pour a few drops of silver nitrate into a sodium metaphosphate solution. Note the colour of the precipitate. See how it reacts with dilute nitric acid. Write the equations of the reactions. In what medium can silver metaphosphate be precipitated ... 

Silver hypophosphate, Ag4P206.—Silver nitrate gives with sodium hypophosphate, Na4P206, a white precipitate of silver hypophosphate. It is also produced in crystalline form by boiling a solution of silver nitrate in nitric acid with phosphorus. Heat decomposes it into silver metaphosphate and metallic silver 3... 

Silver metaphosphate, AgP03.—With a concentrated solution of sodium metaphosphate silver nitrate gives a white precipitate of the semihydrate, AgP03, H20.6 Other metaphosphate have been described.6... 

The monofluorophosphates can be prepared by neutralization of monofluorophosphoric acid (1). Sodium monofluorophosphate [7631 -97-2] is prepared commercially (57) by fusion of sodium fluoride and sodium metaphosphate, and the potassium monofluorophosphate [14104-28-0] can be prepared similarly. Insoluble monofluorophosphates can be readily prepared from reaction of nitrate or chloride solutions with sodium monofluorophosphate. Some salts are prepared by metathetical reactions between silver monofluorophosphate [66904-72-1] and metal chlorides. 

These neutralization processes may be used for the preparation of various complex fluorides without actually isolating the acid or the base. Thus, for example, if equivalent quantities of metallic silver and gold are dissolved in bromine trifluoride and all volatile material is removed in vacuum, the salt AgAuFg remains. The usefulness of this method is increased by the apparent existence in bromine trifluoride solution of both acids and bases which are not sufficiently stable to be isolated. This is well illustrated by the reaction of potassium metaphosphate with bromine trifluoride, which gives a quantitative yield of KPFg ... 

Elemental composition P 38.73%, H 1.26%, O 60.01%. The compound may be identified by physical properties alone. It may be distinguished from ortho and pyrophosphates by its reaction with a neutral silver nitrate solution. Metaphosphate forms a white crystalline precipitate with AgNOs, while P04 produces a yellow precipitate and P20 yields a white gelatinous precipitate. Alternatively, metaphosphate solution acidified with acetic acid forms a white precipitate when treated with a solution of albumen. The other two phosphate ions do not respond to this test. A cold dilute aqueous solution may be analyzed for HPO3 by ion chromatography using a styrene divinylbenzene-based low-capacity anion-exchange resin. 

Ammonium metaphosphates.—The product obtained by H. N. Stokes6 by boiling monamidophosphoric acid, NHa.PO(OH)2, is either ammonium mono-metaphosphate, or a mixture of different metaphosphates—vide infra. G. Tam-mann prepared microscopic crystals of what he called ammonium /3-monometa-phosphate, NH4P08, by crystallization in the cold of a soln. of phosphorus pentoxide and glassy metaphosphoric acid with ammonium carbonate. A soln. of the purified salt gives a white precipitate with silver nitrate. The air-dried salt has the composition NH4P03.3,4H2O and it passes in a few weeks into the orthophosphate. 

Silver nitrate Metaphosphates, P03 White precipitate soluble in dilute nitric acid, dilute ammonia solution, and dilute acetic acid... 

Silver pyrophosphate, Ag4P207.—Precipitation of sodium pyrophosphate with silver nitrate yields the pyrophosphate in the form of a white powder, fusible at red heat. Secondary sodium orthophosphate converts it into silver orthophosphate. A double salt of the formula NaAg3P207 is also known. On heating, its colour changes from white to yellow, a phenomenon which has been attributed to decomposition into sodium metaphosphate and silver orthophosphate, but which is considered by Balareff 4 to have probably a physical origin. 

Into each of two test tubes put 5 c.c. of a solution of disodium orthophosphate and add to one a few drops of silver nitrate solution and to the other a few drops of calcium chloride solution. Kepeat the foregoing tests with the pyrophosphate and metaphosphate solutions prepared in (a) and (5). (2)... 

Liquid phenol. See Phenol Liquid pitch oil. See Creosote oil Liquid Poiy-10] Liquid Poiy-2a, Liquid Poiy-30. See Sodium metaphosphate Liquid rosin. See Tall oil Liquid silver. See Mercury Liquid smoke. See Pyroligneous acid extract Liquid storax. See Storax (Liquidambar orientalis)... 

Silver monofluophosphate is needed in the purification of crude sodium monofluophosphate. It has been prepared by Lange from the ammonium fluoride-phosphorus (V) oxide fusion residues but, using the same general technique, it is more conveniently made from a sodium metaphosphate-sodium fluoride fusion residue. The impurities in such a mixture are the various phosphates whose silver salts are quite insoluble and may be removed from solution as such silver monofluophosphate is prepared by adding solid silver nitrate to the filtrate. 

Hypophosphates are extremely stable to alkali hydroxides. No decomposition occurs in 80% NaOH at 200°C after 1 h, but with fused caustic soda at 320°C there is rapid conversion to orthophosphate (5.244). If silver, mercury or copper hypophosphates are heated below 200°C in nitrogen, decomposition to metal, orthophosphate and a mixture of condensed phosphates occurs. Strong heating gives a mixture of metaphosphate and metal (5.245). 

Bromine(III) fluoride fluorinates everything which dissolves in it. Numerous oxides, halides and salts of oxyacids are converted into fluorides. Carbonates, nitrates and iodates are usually completely converted into the fluorides, while some of the metal oxides, such as BeO, MgO, ZnO or AI2O3 are only partly fluorinated by liquid bromine(III) fluoride. Sodium vanadate yields a mixture of tetrafluorooxovanadate and hexafluorovanadate i, potassium or silver dichromates give KCrOF4 and AgCrOF4 resp. i. Potassium permanganate is converted into KMnFs, potassium metaphosphate into potassium hexafluoro-phosphate and sodium borate into the tetrafluoroborate ... 

In 1963, Caton and Freund (75) made preliminary voltammetric studies of a number of redox systems in molten alkali metal metaphosphates, but the work was limited by the lack of a reference electrode. In 1971 Wolfe and Caton (76) devised a silver reference electrode which was applied to potentiometric and chronopotentiometric studies in equimolar mixtures of sodium and potassium metaphosphates at 700 C of several redox couples. Diffusion coefficients and standard potentials were evaluated. 

Radiation ecologists have attached various types of dosimeters to small animals in an attempt to estimate the radiation dose. Kaye (1965) studied the use of silver-activated metaphosphate-glass dosimeters, which measure dose by radiophotoluminescence, in ecological research at Oak Ridge National Laboratory. These solid-state dosimeters, measuring 1x6 mm, were injected subcutaneously into cotton rats (Sigmodon hispidus) (Figure 19a). The rats were... 

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