Chemical elements
    Physical properties
    Chemical properties
      Boron Hydrides
      Boron trihydride
      Boron halogen
      Boron trifluoride
      Hydrofluoboric acid
      Potassium borofluoride
      Fluoboric acid
      Perfluoboric acid
      Boron subchloride
      Boron trichloride
      Boron tribromide
      Boron tri-iodide
      Oxides of Boron
      Tetraboron trioxide
      Boron dioxide
      Tetraboron pentoxide
      Boron sesqui-oxide
      Boron trioxide
      Boric anhydride
      Boric Acids
      Orthoboric acid
      Boric acid
      Boracic acid
      Complex Boric Acids
      Perboric Acid and Perborates
      Sodium perborate
      Sodium hyperborate
      Potassium perborate
      Rubidium perborate
      Ammonium perborate
      Barium perborate
      Boron sesquisulphide
      Boron trisulphide
      Boron pentasulphide
      Boron selenide
      Boron nitride
      Boron amide
      Boron imide
      Boron phosphide
      Boron phospho-iodides
      Boron carbide
      Boron thiocyanate
      Boron Alkyls
      Boron trimethyl
      Boron Silicides and

Perboric Acid and Perborates

Perboric acid is unknown in the pure state, but it is possible that ethereal solutions have been prepared. A number of metallic perborates, however, are known. They were discovered by Etard, and first prepared in a pure state by Melikoff and Pissarjewsky.

The best known perborates are derivatives of a perboric acid of the composition HBO3. They are readily hydrolysed in aqueous solution, boric acid, or rather its salts, and hydrogen peroxide being produced. Accordingly, the perboric acid is considered to have the constitution O:BO.OH: -

O:BO.OH + 2H2O = B(OH)3 + HO.OH.

This constitution, however, has been disputed on the ground that hydrated podium or potassium perborate does not give off hydrogen peroxide when heated to 50°-60° under diminished pressure or in a current of air free from carbon dioxide; and the alternative constitution has been proposed by Bosshard and Zwicky. The following argument, based upon the preparation and properties of KBO4, is also given by the same chemists. The compound KBO4, or potassium hyperborate, crystallises with 1H2O and is fairly stable. When dried over phosphoric anhydride in vacuo, 4KBO4.H2O is produced, so that the original compound cannot be formulated as KBO3.H2O2. It is rather to be considered as derived from potassium hyperoxide KO.OH, and perboric acid. Hence, two constitutions are possible, viz. KO.O.OB:O and , and it is considered that the latter is much more probable than the former owing to the stability of the salt.

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