Cobalt fluoride, CoF 2.2H 2 0, is formed when cobalt carbonate is evaporated with an excess of aqueous hydrofluoric acid, separating in rose-red crystalline crusts.
Electrolysis of a solution in hydrofluoric acid gives cobaltic fluoride, CoF3.
The dark product obtained is washed with water, hydrochloric acid and hydrofluoric acid, and finally calcined again with the oxide or with borax, being protected from air during the operation by a layer of charcoal.
It may be condensed and yields a solid which melts at - 55° C. Sulphuretted hydrogen decomposes it with formation of hydrofluoric acid and liberation of sulphur.
It is decomposed by water into hydrofluoric and sulphurous acids.
Fluorsulphonic acid, SO 2 F OH, is a mobile liquid obtained by the action of an excess of hydrofluoric acid on well-cooled sulphur trioxide.
Balard completed for many years Berzelius's group of " halogen " elements; the remaining member, fluorine, notwithstanding many attempts, remained unisolated until 1886, when Henri Moissan obtained it by the electrolysis of potassium fluoride dissolved in hydrofluoric acid.
Hydrobromic and hydriodic acids were investigated by Gay Lussac and Balard, while hydrofluoric acid received considerable attention at the hands of Gay Lussac, Thenard and Berzelius.
It is a gas at ordinary temperature; when liquefied it boils at -63.5° C. and on solidification melts at -139° C. Water decomposes it into nitric and hydrofluoric acids.
This salt gives the corresponding chloride and fluoride with hydrochloric and hydrofluoric acids, and the phosphate, Pb(HP04)2, with phosphoric acid.
It is then dissolved in hydrofluoric acid and heated in order to expel silicon fluoride; finally the columbium, tantalum and titanium fluorides are separated by the different solubilities of their double fluorides (C. Marignac, Ann.
Columbium pentafluoride, CbF5, is obtained when the pentoxide is dissolved in hydrofluoric acid.
The salt separates from solutions containing hydrofluoric acid in large plates, which are greenish yellow in colour.
Alkaline and other stannates when treated with aqueous hydrofluoric acid are converted into fluostannates (e.g.
Stannous Fluoride, SnF 2, is obtained as small, white monoclinic tables by evaporating a solution of stannous oxide in hydrofluoric acid in a vacuum.
Stannic Fluoride, SnF 4, is obtained in solution by dissolving hydrated stannic oxide in hydrofluoric acid; it forms a characteristic series of salts, the stannofluorides, M 2 SnF 6, isomorphous with the silico-, titano-, germanoand zirconofluorides.
They pass through a viscous stage in cooling from a state of fluidity; they develop effects of colour when the glass mixtures are fused with certain metallic oxides; they are, when cold, bad conductors both of electricity and heat, they are easily fractured by a blow or shock and show a conchoidal fracture; they are but slightly affected by ordinary solvents, but are readily attacked by hydrofluoric acid.
In the " etching " process the surface of the glass is etched by the chemical action of hydrofluoric acid, the parts which are not to be attacked being covered with a resinous paint.
The surface of the glass had usually been treated with hydrofluoric acid so as to have a satin-like gloss.
Schwanhart of the process of etching on glass by means of hydrofluoric acid, and the rediscovery by J.
Another crystalline form, differing from the former by its solubility in hydrofluoric acid, was prepared by H.
It is only soluble in a mixture of hydrofluoric and nitric acid, or in solutions of the caustic alkalis, in the latter case yielding hydrogen and a silicate: Si-}-2KHO+H 2 O = K 2 SiO 3 +2H 2.
A better method is Wohler's, in which the finely powdered mineral is fused with twice its weight of potassium carbonate in a platinum crucible, the melt powdered and treated in a platinum basin with aqueous hydrofluoric acid.
The filtrate, which may be collected in glass vessels if an excess of hydrofluoric acid has been avoided, deposits the greater part of the salt on cooling.
557.) Titanium fluoride, TiF 4, is a fuming colourless liquid boiling at 284°, obtained by distilling a mixture of titanium oxide, fluorspar and sulphuric acid; by heating barium titanofluoride, BaTiF6 (Emrich, Monats., 1904, 25, p. 907); and by the action of dry hydrofluoric acid on the chloride (Ruff and Plato, Ber., 1904, 37, p. 673).
By dissolving the dioxide in hydrofluoric acid a syrupy solution is obtained which probably contains titanofluoric acid, H 2 TiF 6.
Strontium fluoride, SrF 2, is obtained by the action of hydrofluoric acid on the carbonate, or by the addition of potassium fluoride to strontium chloride solution.
Hydrofluoric acid is the only acid which attacks it.
Filtration in the chemical laboratory is commonly effected by the aid of a special kind of unsized paper, which in the more expensive varieties is practically pure cellulose, impurities like feric oxide, alumina, lime, magnesia and silica having been removed by treatment with hydrochloric and hydrofluoric acids.
Mineral acids generally attack the crystallized metal very little even in the heat; aqua regia, however, dissolves it readily, and so does hydrofluoric acid.
The porcelain-like melt is powdered, boiled with water, and acidified with hydrofluoric acid, and the residual potassium fluosilicate is filtered off.
It is used as a source of hydrofluoric acid, which it evolves when heated with sulphuric acid.
Antimony trifluoride, SbF 3, is obtained by dissolving the trioxide in aqueous hydrofluoric acid or by distilling antimony with mercuric fluoride.
By rapid evaporation of its solution it may be obtained in small prisms. The pentaflhoride SbF 5 results when metantimonic acid is dissolved in hydrofluoric acid, and the solution is evaporated.
The trientoxide, Cu 3 0, is obtained when cupric oxide is heated to 1500 0 -2000° C. It forms yellowish-red crystals, which scratch glass, and are unaffected by all acids except hydrofluoric; it also dissolves in molten potash.
Cuprous fluoride, CuF, is a ruby-red crystalline mass, formed by heating cuprous chloride in an atmosphere of hydrofluoric acid at I g oo°-1200° C. It is soluble in boiling hydrochloric acid, but it is not reprecipitated by water, as is the case with cuprous chloride.
Cupric fluoride, CuF 2, is obtained by dissolving cupric oxide in hydrofluoric acid.
It is soluble in a mixture of nitric and hydrofluoric acids, and the powdered metal, in aqua regia, but slowly attacked by sulphuric, hydrochloric and hydrofluoric acids separately; it is also soluble in boiling potash solution, giving a tunstate and hydrogen.
By using hot acid the yellow anhydrous tungstic acid is precipitated, which is insoluble in water and in all acids except hydrofluoric. It may be obtained in a flocculent form by exposing the hexachloride to moist air.
It forms golden cubes which are unattacked by alkalis or by any acid except hydrofluoric. It appears to be a mixture of which the components vary with the materials and methods used in its production (Philipp, Ber., 1882, 15, p. 499).
- Although the trioxide is soluble in hydrofluoric acid, evaporation of the solution leads to the recovery of the oxide unchanged.
2KF WO 2 F 2 H 2 O, is obtained as crystalline scales by dissolving normal potassium tungstate in hydrofluoric acid and adding potassium hydroxide till a permanent precipitate is just formed.