Chemical elements
  Uranium
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
    Compounds
      Uranium Difluoride
      Uranium Tetrafluoride
      Uranous Oxyfluoride
      Uranium Hexafluoride
      Uranyl Fluoride
      Uranium Trichloride
      Uranium Tetrachloride
      Uranium Pentachloride
      Uranyl Chloride
      Uranyl Chlorate
      Uranyl Perchlorate
      Uranium Tetrabromide
      Uranyl Bromide
      Uranium Tetra-iodide
      Uranyl Iodide
      Uranyl Iodate
      Uranous Oxide
      Uranous Hydroxide
      Uranium Pentoxide
      Urano-uranic Oxide
      Uranium Trioxide
      Ammonium Diuranate
      Ammonium Hexa-uranate
      Hydroxylamine Uranate
      Hydroxylamine Potassio-uranate
      Barium Uranate
      Barium Diuranate
      Bismuth Uranate
      Iron Uranate
      Lithium Uranate
      Potassium Uranate
      Potassium Diuranate
      Potassium Tetra-uranate
      Potassium Hexa-uranate
      Rubidium Uranate
      Silver Diuranate
      Sodium Uranate
      Sodium Diuranate
      Sodium Triuranate
      Sodium Penta-uranate
      Strontium Uranate
      Zinc Uranate
      Peruranic acid
      Ammonium Peruranate
      Barium Peruranates
      Lithium Peruranate
      Nickel Peruranate
      Potassium Peruranate
      Sodium Peruranates
      Uranium Monosulphide
      Uranium Sesquisulphide
      Uranium Disulphide
      Uranium Oxysulphide
      Uranyl Sulphide
      Uranium Sulphite
      Uranyl Sulphite
      Complex Uranyl Sulphites
      Uranium Sulphate
      Uranium Dithionates
      Uranyl Sulphate
      Uranyl Pyrosulphate
      Uranyl Thiosulphate
      Uranyl Dithionate
      Uranium Sesquiselenide
      Uranium Diselenide
      Uranyl Selenide
      Uranyl Selenite
      Uranyl Selenate
      Uranium Telluride
      Uranium Nitrides
      Uranous Nitrate
      Uranyl Nitrate
      Uranium Monophosphide
      Uranous Phosphide
      Uranyl Hypophosphite
      Uranyl Phosphite
      Uranous Phosphates
      Uranyl Phosphates
      Complex Uranyl Phosphates
      Uranyl Aminophosphates
      Uranous Arsenide
      Uranyl Metarsenite
      Uranous Arsenate
      Uranyl Arsenates
      Complex Uranyl Arsenates
      Uranous Antimonide
      Uranous Antimonate
      Uranium Carbide
      Complex Uranyl Carbonates
      Ammonium Uranyl Carbonate
      Calcium Uranyl Carbonate
      Potassium Uranyl Carbonate
      Sodium Uranyl Carbonate
      Thallium Uranyl Carbonate
      Potassium Uranyl Ferrocyanide
      Uranyl Platinocyanide
      Uranyl Cyanate
      Uranyl Thiocyanate
      Uranium Silicide
      Uranium Boride
      Uranyl Perborate
    PDB 1anv-3pu4

Uranous Phosphates





Uranous orthophosphate, U3(PO4)4

Uranous orthophosphate, U3(PO4)4, is prepared by adding trisodium phosphate to a solution of uranous chloride in an atmosphere of carbon dioxide. It separates as an amorphous precipitate, which, when heated to redness in a current of hydrogen chloride, changes to a green microcrystalline powder. A basic phosphate, of composition U2O(PO4)2 or 2UO2.P2O5, is obtained as a bright green powder when uranyl ortho- or pyro-phosphate is reduced by heating in hydrogen; it becomes crystalline when ignited in hydrogen chloride. The same compound may be obtained by precipitating a solution of uranous chloride by means of excess of trisodium phosphate or sodium pyrophosphate. A chlorophosphate, UClPO4 or 3UO2.UCl4.2P2O5, is obtained by passing the vapour of uranous chloride over heated metaphosphoric acid, or any one of the uranous phosphates, after displacement of the air by carbon dioxide. It yields green orthorhombic crystals,

a:b:c = 0.8376:1:0.7473.

An acid uranium phosphate, UH2(PO4)2 or UO2.P2O5.H2O, is obtained as a gelatinous precipitate when ordinary sodium phosphate, or excess of sodium metaphosphate, is added to a solution of uranous chloride. It may be obtained in the crystalline form as UH2(PO4)2.5H2O. Aloy also describes a uranous chlorophosphate of composition UH2(PO4)2.UCl4.


Uranous metaphosphate, U(PO3)4

Uranous metaphosphate, U(PO3)4, is prepared by heating to redness a mixture of uranous oxide and metaphosphoric acid; the operation should be carried out in a gold Rose crucible through which carbon dioxide is passed. After washing the product with water and boiling nitric acid, green crystals of the metaphosphate remain. The same compound is obtained when uranium orthophosphate is fused with four times its weight of metaphosphoric acid; or when anhydrous uranyl sulphate is dissolved in metaphosphoric acid at 316° C. Uranous metaphosphate yields emerald-green rhombic crystals, isomorphous with the corresponding thorium salt and of density 3.9 at 0° C. It is only slowly attacked by acids, but fused alkalies or alkali chlorides decompose it. When heated strongly, it melts, loses phosphorus pentoxide, and yields the pyrophosphate.

Uranous pyrophosphate, UP2O7

Uranous pyrophosphate, UP2O7, may be obtained by heating uranous hydrogen phosphate, UH2(PO4)2.5H2O, in a current of carbon dioxide; or more readily, by calcining the uranyl salt, UO2H4(PO4)2.3H2O, in an atmosphere of hydrogen. The product is amorphous but becomes crystalline without change in composition on heating in a stream of hydrogen chloride. The crystalline form may also be obtained by passing the vapour of phosphorus oxychloride over urano-uranic oxide. The crystals are not well defined and are almost colourless. The trihydrate, UP2O7.3H2O, is formed according to Rammelsberg as a gelatinous precipitate by the addition of sodium pyrophosphate to a solution of uranous chloride.

Complex phosphates of uranium and the alkali or alkaline earth metals have been prepared by fusing an intimate mixture of the alkali phosphate with an excess of uranous oxide in a platinum Rose crucible through which carbon dioxide was passing. The fusion may be facilitated by the addition of a little alkali chloride. On slowly cooling the crucible, well-defined crystals of the double phosphate are formed. If the alkali metaphosphate is used, salts of the type R2U(PO4)2 where R = K, Na; R2 = Ca, Sr, Ba, are obtained.

The potassium salt, K2U(PO4)2, forms green, orthorhombic crystals,

a:b:c = 0.3711:1:0.3902,

and is soluble in concentrated acids.

The sodium salt, Na2U(PO4)2, is better prepared from the pyrophosphate, using excess of sodium chloride. It forms emerald-green, orthorhombic crystals,

a:b:c = 0.6766:1:0.4006,

and is readily attacked by acids.

The calcium salt, CaU(PO4)2, forms green monoclinic crystals,

a:b:c = 1.508:1:1.124; γ = 93° 29'.

The barium salt, BaU(PO4)2, forms thin green hexagonal plates.

The strontium salt, SrU(PO4)2, forms orthorhombic crystals,

a:b:c = 1.474:1:1.165.

By using the alkali pyrophosphates, the potassium and sodium salts of the type Ri2U3(PO4)8, or 6R2O.3UO2.4P2O5, are obtained.

The salt, KU2(PO4)3 or K2O.4UO2.3P2O5, is obtained by heating the orthophosphate, K2HPO4, with a slight excess of potassium uranium chloride; it forms small dark green crystals. The corresponding sodium salt is prepared by fusion of sodium metaphosphate with excess of uranous oxide.
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