Chemical elements
  Platinum
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Platinum Difluoride
      Platinum Tetrafluoride
      Platinum Dichloride
      Tetrachlor~platinous Acid
      Tetrachlor-platinites
      Potassium Tetrachlor-platinite
      Trichlor-hydroxy-platinous Acid
      Silver Trichlor-hydroxy-platinite
      Platinum Trichloride
      Caesium Pentachlor-platinite
      Platinum Tetrachloride
      Ammonium Chlor-platinate
      Caesium Chlor-platinate
      Potassium Chlor-platinate
      Rubidium Chlor-platinate
      Silver Chlor-platinate
      Sodium Chlor-platinate
      Pentachlor-hydroxy-platinic Acid
      Barium Pentachlor-hydroxy-platinate
      Silver Pentachlor hydroxy-platinate
      Tetrachlor-dihydroxy-platinic Acid
      Dichlor-tetrahydroxy-platinic Acid
      Monochlor-pentahydroxy-platinic Acid
      Platinum Dibromide
      Brom platinous Acid
      Brom-platinic Acid
      Platinum Di-iodide
      Platinum Tetra-iodide
      Iodo-platinic Acid
      Ammonium Iodoplatinate
      Potassium Iodo-platinate
      Sodium Iodo-platinate
      Tetra-iodo-dihydroxy-platinic Acid
      Platinum Monoxide
      Triplatinum Tetroxide
      Platinum Sesquioxide
      Platinum Dioxide
      Hexahydroxy-platinic Acid
      Platinum Trioxide
      Platinum Monosulphide
      Platinum Sesquisulphide
      Platinum Disulphide
      Potassium Thio-platinate
      Platinum Oxysulphide
      Platinum Disulphate
      Platinum Monoselenide
      Platinum Triselenide
      Platinum Subtelluride
      Platinum Monotelluride
      Platinum Ditelluride
      Ammonium Platinonitrite
      Potassium Platinonitrite
      Silver Platinonitrite
      Platinum Subphosphide
      Platinum Monophosphide
      Platinum Diphosphide
      Platinum Arsenide
      Platinum Di-antimonide
      Monocarbonyl Platinum Dichloride
      Sesquicarbonyl Platinum Dichloride
      Dicarbonyl Platinum Dichloride
      Diphosgene Platinum Dichloride
      Carbonyl Platinum Dibromide
      Monocarbonyl Platinum Di-iodide
      Carbonyl Platinum Monoxide
      Carbonyl Platinum Monosulphide
      Carbonyl Platinum Thiocyanate
      Platinous Cyanide
      Cyanoplatinous Acid
      Platinocyanides
      Aluminium Platinocyanide
      Ammonium Platinocyanide
      Barium Platinocyanide
      Calcium Platinocyanide
      Cerium Platinocyanide
      Copper Platinocyanide
      Hydrazine Platinocyanide
      Hydroxylamine Platinocyanide
      Indium Platinocyanide
      Lead Platinocyanide
      Magnesium Platinocyanide
      Potassium Platinocyanide
      Radium Barium Platinocyanide
      Rubidium Platinocyanide
      Sodium Platinocyanide
      Sodium Potassium Platinocyanide
      Strontium Platinocyanide
      Uranyl Platinocyanide
      Dichlorcyanoplatinic Acid
      Cyanoplatinic Acid
      Lithium Platinicyanide
      Potassium Platinicyanide
      Silver Platinicyanide
      Potassium Thiocyanoplatinite
      Ammonium Thiocyanoplatinate
      Potassium Thiocyanoplatinate
      Potassium Selenocyanoplatinate
      Platinum Subsilicide
      Platinum Monosilicide
    Catalyst
    PDB 1a2e-2bho
    PDB 2ch8-3un9
    PDB 3vdk-5bna

Platinum Trioxide, PtO3






Platinum Trioxide, PtO3, has been obtained by electrolysing a well-cooled solution of hydrated platinum dioxide in 2-Normal potassium hydroxide, using platinum electrodes. The anode becomes covered with an amorphous, golden-coloured film of potassium platinate, having the composition K2O.PtO3 or K2PtO4. This, by treatment with ice-cold, dilute acetic acid, yields the free trioxide as a reddish brown substance, which gradually loses oxygen, but never becomes the pure dioxide on simply keeping in air, probably because a solid solution of trioxide in the dioxide is formed.

Platinum trioxide is not acted upon by dilute sulphuric, nitric, or acetic acid. Dilute hydrochloric acid dissolves it with evolution of chlorine, whilst sulphurous acid converts it into complex sulphites.

Concentrated hydrochloric acid rapidly dissolves the trioxide with violent chlorine evolution, whilst concentrated sulphuric and nitric acids slowly convert it into the dioxide in the warm.

When gently warmed oxygen is evolved, a residue of platinum dioxide being obtained.

A remarkable feature of the trioxide is the fact that it is not reduced by hydrogen peroxide, and Wohler therefore regards it, not as a peroxide, but as the anhydride of platinic acid, in which the platinum is regarded as hexavalent, thus:



It is suggested that the anodic passivity of platinum is attributable to the formation of a surface film of this oxide.


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