Chemical elements
  Antimony
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
    Compounds
      Antimony Trihydride
      Antimony Trifluoride
      Antimony Pentafluoride
      Antimony Trichloride
      Oxychlorides of Tervalent Antimony
      Antimony Tetrachloride
      Antimony Pentachloride
      Chloroantimonic Acids
      Antimonyl Perchlorate
      Antimony Tribromide
      Antimony Oxybromides
      Antimony Pentabromide
      Antimony Triiodide
      Antimony Oxyiodide or Antimonyl Iodide
      Antimony Thioiodide
      Mixed Antimony Halides
      Antimony Trioxide
      Hydrated Antimony Trioxide
      Antimonites
      Antimony Tetroxide or Antimony Dioxide
      Antimony Pentoxide
      Antimony Trisulphide
      Antimony Pentasulphide
      Thioantimonates
      Normal Antimony Sulphate
      Potassium Stibiothiosulphate
      Antimony Selenate
      Antimony tritelluride
      Antimony Phosphide
      Antimonyl Dihydrogen Phosphite
      Antimony Phosphate
      Antimony Pyrophosphate
      Antimony Thiophosphate
    PDB 1exi-2xqa

Antimony Trifluoride, SbF3






Antimony Trifluoride, SbF3, was first prepared by Berzelius in 1824 by evaporating a solution of antimony trioxide in hydrofluoric acid; Dumas prepared the same compound in 1826 by distilling a mixture of mercuric fluoride and powdered antimony. It has also been prepared by heating antimony trichloride with hydrofluoric acid in the presence of an organic solvent. Metallic antimony does not dissolve in concentrated hydrofluoric acid.

Antimony trifluoride is most conveniently prepared by the method of Berzelius. Pure antimony trioxide is dissolved in excess of hydrofluoric acid, and the solution is evaporated until a film forms on the surface. On cooling, long, needle-shaped crystals separate out. These may be dried between filter-paper and stored in vessels of gutta-percha or platinum.

Antimony trifluoride forms colourless, transparent, rhombic crystals of density (at 20.9° C.) 4.379. Its melting point is 292° C. or slightly lower; it sublimes when heated in a platinum vessel. The solubility in water is as follows:

t° C0202530
SbF3 (grams per 100 grams water)384.7451.0494.0565.6


The solubility is increased by the presence of hydrofluoric acid and of alkali salts.

The heat of formation of antimony trifluoride is 144,300 gram- calories. It does not fume in air, but when heated it volatilises with partial decomposition, leaving a residue of antimony trioxide. It is very hygroscopic. If an aqueous solution is evaporated without the addition of hydrofluoric acid, some antimonyl fluoride is obtained; no hydrolysis is apparent, however, below 30° C.

Chlorine reacts with antimony trifluoride forming the compound 2SbF5.SbCl5.

Liquid ammonia reacts with antimony trifluoride to form the di-ammoniate, SbF3.2NH3. This is a yellow powder jvhich loses ammonia in the presence of moist air.

Antimony trifluoride shows a tendency to form double and complex salts. From the thermochemical examination of solutions in hydrofluoric acid, Guntz concluded that an acid fluoride is formed, but was unable to isolate it. Beck concluded that the most stable complex formation is of the type MSbF4 or SbF3.MF, in which the antimony is tervalent.

Numerous double compounds are formed with alkali fluorides, either by crystallisation from solutions of the mixed salts, or by addition of alkali carbonate to a solution of antimony trioxide in hydrofluoric acid. Salts in which the ratio SbF3:MF has the following values have been obtained: 4:1, 3:1, 2:1, 7:4, 1:1, 1:2 and 1:3. They are colourless, crystalline compounds and contain no combined water; they are fairly stable in air, and dissolve readily in water without producing turbidity; the solutions are acid, and attack glass. The salts can be regained from these solutions by evaporation.

Double compounds with alkali chlorides and sulphates have also been obtained, having the general formulae MCl.SbF3, M2SO4.SbF3, 3M2SO4.4SbF3 and M2SO4.2SbF3, where M represents a univalent metal. They may be prepared by the first method mentioned above, by the action of basic antimony sulphate on the corresponding fluoride, or by the action of alkali sulphate upon antimony trifluoride in the presence of hydrochloric acid. In general they crystallise fairly well, without combined water; they are fairly stable and not hygroscopic. Their solutions in water are strongly acid and attack glass.

Other double compounds have also been obtained. In some cases there is evidence for the existence of a complex ion in solution, but not in others. Solutions containing potassium nitrate, potassium sulphate or oxalic acid give no evidence of a complex ion; while solutions containing normal sodium oxalate or tartrate, ammonium oxalate or potassium antimonyl tartrate indicate decidedly the formation of such ions. The following crystalline compounds have been obtained: 3KNO3.SbF3, 4(NH4)2C2O4.2SbF3, 2Na2C2O4.3SbF3 and K3SbO(C2O4)2.SbF3.8H2O.

Salts containing antimony trifluoride have been used as mordants; but only those salts which yield complex ions in dilute solution are suitable for such purpose.


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