Chemical elements
  Titanium
    Isotopes
    Energy
    Preparation
    Physical Properties
    Chemical Properties
      Titanium Trifluoride
      Titanium Tetrafluoride
      Hydrofluotitanic acid
      Potassium Titanifluoride
      Sodium Titanifluoride
      Titanium Dichloride
      Titanium Trichloride
      Titanium Tetrachloride
      Titanic Chloride
      Titanium Oxychlorides
      Hydrochlorotitanic Acid
      Addition Compounds of Titanium Tetrachloride
      Titanium Tribromide Hexahydrate
      Titanium Tetrabromide
      Titanic Bromide
      Hydrobromotitanic Acid
      Titanium Chlorobromides
      Titanium Di-iodide
      Titanium Tri-iodide
      Titanium Tetra-iodide
      Titanic Iodide
      Titanium Monoxide
      
Titanium Sesquioxide
      Titanium Dioxide
      Titanic Oxide
      Titanic Hydroxides
      Metatitanic Acid
      Titanates
      Titanium Monosulphide
      Titanium Sesquisulphide
      Titanium Disulphide
      Titanium Sulphates
      Titanous Sulphate
      Titanium Sesquisulphate
      Complex Sulphates of Tervalent Titanium
      Normal Titanic Sulphate
      Potassium Titanisulphate
      Potassium and Ammonium Titanylsulphates
      Titanous Nitride
      Titanic Nitride
      Titanamide
      Titanium Nitrogen Halides
      Titaninitric Acid
      Titanium Phosphide
      Titaniphosphoric Acid
      Titanium Carbide
      Titanium Cyanonitride
      Titanium Thiocyanates
      Titanium Sesquioxalate
      Titanitartrates and Allied Salts
      Titanium Silicide
      Pertitanates

Metatitanic Acid, TiO(OH)2






Metatitanic Acid, TiO(OH)2, insoluble in hydrochloric acid, is obtained by various means from hot solutions. Thus when an aqueous solution of titanic chloride is boiled the meta-acid is gradually precipitated; this precipitation takes place the more readily in presence of sulphuric acid or a soluble sulphate owing to the inferior stability of titanic sulphate; similarly, the soluble product of fusion of a titanic mineral with potassium hydrogen sulphate yields metatitanic acid when boiled with water. The hydrolysis of a slightly acidified solution of titanic sulphate which occurs on boiling is quantitative, and is employed for the estimation of titanium.

Metatitanic acid is also formed when a hot acid solution of a titanic compound is precipitated by alkali, as well as by the action of nitric acid of density 1.25 on metallic titanium. Although practically insoluble in dilute acids, metatitanic acid forms an opalescent, colloidal suspension with water, whence it is precipitated by acids and salt solutions.

When ignited, the meta-acid passes into the anhydride without evolving light.

The assumption of the colloidal state by metatitanic acid suggests that the molecules of this substance are complex. Colloidal titanic acid has been obtained in other ways. On adding hydrochloric acid to the mass obtained by fusing titanic oxide with alkali, Rose obtained a jelly consisting of the hydrated oxide; whilst Knop found that the white precipitate formed on adding ammonia to a solution of titaniferous magnetite, in presence of tartaric acid added to keep the iron in solution, swelled to a transparent jelly when washed with water. Graham, also, obtained colloidal titanic acid as a hydrosol, by the dialysis of a hydrochloric acid solution of the ortho-acid, and this on concentration yields a hydrogel. Thus it appears that in its colloidal properties titanic acid closely resembles silicic acid; moreover, the question arises whether the simple formulae Ti(OH)4 and TiO(OH)2 can properly be applied to the two hydrates of titanic oxide which are respectively soluble and insoluble in hydrochloric acid, or whether the molecules of these two substances, being very complex, approximate to rather than correspond exactly in composition with these formulae. According to Carnelley and Walker, who have examined the influence of the gradual increase of temperature upon these and other hydrates, the regular form of the curves obtained with titanic as well as silicic hydrate is against the existence of definite hydrates of any evident degree of stability.


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