Chemical elements
  Tin
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Tetramethyl Stannane
      Methyl stannic chloride
      Tin Tetra-ethyl
      Tin Tri-ethyl
      Stannous Fluoride
      Stannic Fluoride
      Sodium Stannifluoride
      Potassium Stannifluoride
      Ammonium Stannifluoride
      Stannous Chloride
      Stannic Chloride
      Chlorostannates
      Stannous Bromide
      Stannic Bromide
      Stannous Iodide
      Stannic Iodide
      Mixed Stannic Halides
      Stannous Oxide
      Stannous Hydroxide
      Stannic Oxide
      Potassium Stannate
      Stannic Acid and its Derivatives
      Parastannic Acid
      Stannyl Chloride
      Parastannyl Chloride
      Stannous Sulphide
      Stannic Sulphide
      Stannic Oxysulphide
      Stannic Iodosulphide
      Stannous Sulphate
      Stannic Sulphate
      Stannic Nitrate
      Stannous Nitrate
      Phosphor-tin
      Stannioxalic Acid
      Stannous Tartrate
      Tin and Silicon
      Stannous Tungstate
    PDB 3e94-3kwy

Stannic Bromide, SnBr4






Stannic Bromide, SnBr4, is formed from its elements, which combine with evolution of light and heat. It is best prepared, according to Lorenz, by dropping bromine from a capillary tube on to strips of tin contained in a distilling flask, removing excess of bromine by warming the flask, and then distilling the bromide, which, so obtained, is a snow-white crystalline mass. The physical constants of this substance are not known with certainty, owing to the different values obtained by different observers. Carnelley and O'Shea determined the vapour density to be 229 (theory requires 219 when H = 1), and the melting-point 30° C., whilst for the latter, Raymann and Preis found 33° C., and Garelli 29.45° C. The boiling-point is 203.3° C. (Raymann and Preis), or 201° C. (Carnelley and O'Shea, Lorenz, Neumann); and the density of the liquid at 35° C. is 3.349 (Raymann and Preis), and at 39° C. 3.322 (Bodeker). Berthelot estimated the heat of formation of stannic bromide to be:

[Sn] + 4Br = [SnBr4] + 98,000 calories,
and
[Sn] + (4Br) = [SnBr4] + 112,800 calories.

Because it has a high molecular depression, and a convenient melting- point, this substance has been employed by Garelli in cryoscopic determinations, the molecular depression being estimated to be 280. According to Tolloczko, however, the value should be 305.

Stannic bromide fumes in the air, and is readily soluble in cold water. From this solution the hydroxide separates slowly on standing and quickly on boiling. Nevertheless the hydrate SnBr4.4H2O is obtained when an aqueous solution of the anhydrous bromide is evaporated over sulphuric acid (Raymann and Preis).

With ammonia stannic bromide forms the additive compound SnBr4.2NH3 (Raymann and Preis).

Bromostannic Acid exists. According to Raymann and Preis it is H2SnBr6.8H2O, but Seubert gives it the formula H2SnBr6.7H2O. Alkali stannibromides are known.


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