Ammonium phosphate, decompositions

Fluorhydroxyapatite can be synthesised by the traditional double-decomposition method generally used for apatite precipitation. An ammonium phosphate and fluoride solution (solution B) is added, dropwise, into a hot (generally at boiling temperature) calcium solution (solution A) at a basic pH level as previously published [122,123]. Fluorapatites close to stoichiometry are obtained (a = 2, see the following reaction equation) however, a very small residual amount of OH always seems to be present. Filtration and several washing operations are necessary to remove the counter-ions. The reaction is almost total due to the very low solubility of fluorhydroxyapatites. 

Oxamide, This diamide is sparingly soluble in water and insoluble 111 various organic solvents. It melts at about 350°C, with accompanying decomposition. Because of the low solubility in water, the compound is granulated and used as a slow-release nitrogen fertilizer. Conventional nitrogen ferdlizers such as ammonium sulfate, urea, ammonium nitrate, and ammonium phosphate, are soluble in water, and thus are easily lost as... 

When an aq. soln. of trimetaphosphimic acid, or of one of its salts, acidified with one of the stronger mineral acids, is heated or kept for a long time, decomposition occurs—slowly if cold, rapidly if heated. Orthophosphoric acid and ammonia (ammonium phosphate) are the ultimate products of the decomposition. Several intermediate products have been detected in addition to pyrophosphoric acid, what H. N. Stokes calls diimidotriphosphoric acid, and imidodiphosphoric acid have been found, and he represents the different stages of the decomposition ... 

The early workers on phosphorus prepared that element from urine which normally contains ammonium and sodium phosphates. Thus, R. Boyle1 evaporated the urine to a syrupy consistency, and distilled the product either alone or admixed with sand or charcoal. The carbon produced by the decomposition of the organic matter in the urine, or added to it in the form of charcoal, decomposes the ammonium phosphate, without affecting the sodium phosphate. A. S. Marggraf mixed the cone, urine with lead chloride and charcoal powder, and heated the mass until it became pulverulent. The ammonium and sodium phosphates were converted into lead phosphate, and on distillation, the carbon liberated the phosphorus from the lead phosphate. G. A. Giobert mixed the unevaporated urine with lead nitrate or acetate washed the precipitated mixture of lead phosphate and sulphate mixed the precipitate with charcoal and distilled the dried product. 

The results of the characterization of the product synthesized with Fourier transformation infra-red spectrophotometer (FTIR), X-ray diffractometer (XRD), scanning electron mirror microscope (SEM) and the transmission electron mirror microscope (TEM) illustrate that the product synthesized by the process of double decomposition-precipitation with calcium nitrate and di-ammonium phosphate as the reactants in the SCISR consists of well dispersed particles of about 15 nm in diameter and 50-70 nm long, having a very regular shape and appearance and is confirmed to be hydroxylapatite. 

Nitric Phosphate. Fertilizers that are referred to as nitric phosphate or nitrophos-phate are produced by acidulation of phosphate rock with nitric acid or with mixtures of nitric and sulfuric or phosphoric acids. The primary advantage of nitric phosphate processes is that no sulfur or less sulfur is required as compared with superphosphates or ammonium phosphates this is particularly important during a shortage of sulfur, or in locations where sulfur must be shipped long distances. A variety of processes and equipment have been used in Europe since the late 1930s.3,12 Also there are a number of plants in Central and South America and in Asia. The production of nitric phosphates is complex. Simple substitution of nitric acid in a superphosphate-type acid-rock reaction is not feasible because (1) decomposition of the nitric acid would occur and cause noxious fumes and loss of nitrogen and (2) the product would be extremely hygroscopic and unstable. 

The ordinary salt, secondary ammonium phosphate, (NH4)2HP04, is prepared by concentrating a solution of phosphoric acid with addition of sufficient ammonia to prevent the development of an acidic reaction. It forms monoclinic crystals,8 of density 1-6199 or 1-678.10 It readily loses ammonia, with formation of the primary phosphate, the decomposition being rapid at 166° C.11 Above this temperature the primary phosphate is transformed into pyrophosphate. The aqueous solution of the secondary phosphate has a strongly alkaline reaction, and is decomposed by boiling, with evolution of ammonia and formation of the primary salt. 

The trivalent orthophosphate anion (PO/ ) readily forms double salts, so that the number of reactants available is very large. Studies have included the decompositions of many acid salts, and acid salts may also be generated during decomposition of ammonium salts following the release of ammonia gas. Comparisons between the decomposition behaviour of related compounds (e.g. metal and acid salts) can yield useful mechanistic information. Removal of water often yields pyrophosphates or metaphosphates. Some higher molecular mass substances form glassy phases and these crystallize only with difficulty. The decompositions of ammonium phosphates are considered in Chapter 15. 

AMMONIUM PHOSPHATE or sec-AMMONIUM PHOSPHATE or AMMONIUM PHOSPHATE, DIBASIC or AMMONIUM PHOSPHATE, MONOBASIC (7783-28-0, dibasic 7722-76-1,monobasic) HgN04P (monobasic) H9N2O4P (dibasic) Noncombustible solid. Contact with air slowly forms anhydrous ammonia. Contact with caustics forms anhydrous ammonia gas. Violent reaction with strong oxidizers, potassium chlorate sodium hypochlorite strong bases. Reacts with antimony(V) pentafluoride lead diacetate magnesium, silver nitrate zinc acetate. Heat of decomposition produces toxic fiimes of ammonia and phosphorus oxides. 

Dibasic ammonium phosphate melts with decomposition at 155°C. 

In the presence of urea, ammonium phosphates will polymerise to metaphosphates below the temperature required for their decomposition to ammonia and phosphoric acid (Section 5.4) (Figure 5.4a,b). 

The usual method of blowpipe analysis was to direct the flame on to a small portion of the material on a charcoal block. The substance under investigation was often mixed with sodium carbonate, borax, or microcosmic salt (sodium ammonium phosphate). When the material was heated alone or with sodium carbonate, it often yielded decomposition products with a characteristic appearance and borax or microcosmic salt fused to a glass to which the unknown material might impart a characteristic colour. After Wollaston had introduced a method of producing malleable platinum in 1800, a platinum wire was frequently used to support the material in blowpipe analysis, particularly in the production of glassy beads with borax and microcosmic salt. 

In particular, Horrocks and co-workers [50] have demonstrated that Mn and Zn shift the thermal degradation of ammonium polyphosphate (APP) towards lower temperatures, so that flame retardancy is induced at lower temperatures. Similar results were observed also employing other transition metal ions, such as Cu(II), Zn(II), Fe(II), Co(II), Cr(III), Ce(IV), La(III), Y(III) and Ho(III) or Mn(II), Pb(II), Bi(III), in combination with cellulose ammonium phosphate, as reported by Tian et al. [51, 53]. Indeed, the temperature of cellulose decomposition was lowered in the presence of metal complexes of cellulose ammonium phosphate with respect to samples not treated by metal ions furthermore, the values of char yield were greater for samples treated with Ho and Ce + [51] and Mn +, Pb + and BF+ [53] as compared to the untreated coxmterparts. 

Phosphoms oxyfluoride is a colorless gas which is susceptible to hydrolysis. It can be formed by the reaction of PF with water, and it can undergo further hydrolysis to form a mixture of fluorophosphoric acids. It reacts with HF to form PF. It can be prepared by fluorination of phosphoms oxytrichloride using HF, AsF, or SbF. It can also be prepared by the reaction of calcium phosphate and ammonium fluoride (40), by the oxidization of PF with NO2CI (41) and NOCl (42) in the presence of ozone (43) by the thermal decomposition of strontium fluorophosphate hydrate (44) by thermal decomposition of CaPO F 2H20 (45) and reaction of SiF and P2O5 (46). 

Nutrients are usuaUy added at concentrations ranging from 0.005 to 0.02% by weight (16). In a field appHcation using hydrogen peroxide, nutrients were added to the injected water at the foUowing concentrations 380 mg/L ammonium chloride 190 mg/L disodium phosphate, and 190 mg/L potassium phosphate, the latter used primarily to complex with iron in the formation to prevent decomposition of hydrogen peroxide (24). 

Although many ammonium metal phosphates are known, few kinetic studies of their decompositions have been reported and no systematic investigations of the influence of metal ion or structure on the deammi-nation reactions are available. Thermal analyses [971] of compounds of the type MNH4P04 xH20 (where M is a divalent metal) show that, after dehydration, there is a continuous and simultaneous evolution of NH3 and H20 [137], maintained until crystalline M2P207 is formed, e.g. 

---