Only one compound of hydrogen and fluorine is known, namely hydrofluoric acid, HF or H2F2, which was first obtained by C.
The salts of hydrofluoric acid are known as fluorides and are easily obtained by the action of the acid on metals or their oxides, hydroxides or carbonates.
It is used as a source of hydrofluoric acid, which it evolves when heated with sulphuric acid.
Moissan in 1886 by the electrolysis of pure anhydrous hydrofluoric acid containing dissolved potassium fluoride.
Fired tints and lustres can be removed with hydrofluoric acid.
As fluor spar, CaF{2}, and as hydrofluoric acid, HF.
For the same reason tin, in acting on hydrochloric acid, evolves hydrogen, and silicon does the same with hydrofluoric acid.
Neither hydrochloric, hydrobromic, nor hydriodic acid acts on sand and glass, whilst hydrofluoric acid corrodes them, forming gaseous silicon fluoride.
Thus by the action of hydrofluoric acid on manganese peroxide, or by decomposing a solution of hydrofluoric acid by an electric current, either oxygen or a mixture of oxygen and fluorine were obtained instead of fluorine.
Cryolite, like fluor spar, is also insoluble in water, and gives hydrofluoric acid with sulphuric acid.
The addition of the sulphuric acid displaces the hydrofluoric acid, and it may be assumed that the resulting sulphates (usually of iron or aluminium) are converted to oxides by the final ignition.
It is tested by volatilisation of the silica as silicon fluoride after solution in hydrofluoric acid, and, if the analysis has been properly conducted, the residue, after treatment with the acids and ignition, should not exceed 1 mg.
It is obvious that unless the sulphuric and hydrofluoric acids used are known to leave no residue on evaporation, a quantity equal to that employed in the analysis must be evaporated and a correction applied for any residue found.
The mark may be etched upon the flask by hydrofluoric acid, or by the use of an etching ink now commonly sold on the market.
According to Hickling (36) the product of the action of hydrofluoric acid 'has not the remotest resemblance to china clay.
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.
Solution of hydrofluoric acid did not appear to be decomposed under the influence of the electric current: it was the water which gave way apparently.
While heating it you will perceive bitter-smelling vapors of hydrofluoric acid, which come in contact with the glass where the wax has been scraped off.
When you try this chemical experiment, do not inhale the vapors of the hydrofluoric acid, for they are very injurious, and burn the skin very badly.
For deep etching, hydrofluoricacid is diluted with 1½ vols.
Note: Fluorine unites with hydrogen to form hydrofluoric acid, which is the agent employed in etching glass.
Ammonium fluoride, NH4F, may be obtained by neutralizing ammonia withhydrofluoric acid.
The salt separates from solutions containing hydrofluoric acid in large plates, which are greenish yellow in colour.
Columbium pentafluoride, CbF5, is obtained when the pentoxide is dissolved inhydrofluoric acid.
It is then dissolved inhydrofluoric 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.
A body of glass being formed of layers of different colours, the outer layer or layers are partially removed by eating away by hydrofluoric acid, and the remaining portions are then wrought into designs with the chisel or graver.
The process of etching by hydrofluoric acid, has been largely developed as a means of ornamenting glass, and has to a large extent superseded engraving.
The sand blast is used too in the production of an imitation of engraved glass, in embossing glass as a substitute for hydrofluoric acid, and for re-cutting old files.
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.
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.
With ordinary dry-plates the method usually recommended is to immerse them in dilutehydrofluoric acid.
A few drops of hydrofluoricacid are added to the water, and the dish gently rocked.
A thin film of gelatine is moistened in a dilute solution of hydrofluoric acid, one part of acid to sixty of water.
If the latter experiment is tried in a closed glass tube the formation of the hydrofluoric acid is made evident by the etching and clouding of the walls of the tube.
It is not affected by hydrochloric acid, but is partially decomposed by sulphuric acid and then yields hydrofluoric acid.
Hydrofluoric acid is used for etching glass and opening up silicates.
They may be dissolved in hydrofluoric acid either at once or after fusion with bisulphate of potash, and extraction with cold water.
In larger amounts they are recognised by the property hydrofluoric acid has of etching glass.
This is a white powder, which is insoluble in acids; even in hydrofluoric acid it is only slightly attacked.
To the solution in hydrofluoric acid gradually add a boiling solution of acid potassium fluoride (HF, KF.
The two washed alumina precipitates are dried and placed in the platinum crucible containing the residue from silica after treatment with hydrofluoric acid.
Mixed with hydrochloric acid it may sometimes be used instead of hydrofluoric acid.
The residue, after weighing, may be treated with hydrofluoric and sulphuric acids for any silica,[114] which would be determined by loss.
The finely ground mineral mixed with dilute sulphuric acid is treated on a water bath with hydrofluoric acid.
After weighing it is treated with hydrofluoric acid and a little sulphuric, carefully evaporated and ignited strongly.
We recall here that the manipulation of hydrofluoricacid requires great prudence.
The glass is then exposed about five minutes to the vapors of hydrofluoric acid, which roughens the spaces between the lines, and leaves the polish on the surface under the fat.
This is hydrofluoric acid, a dilute solution of which attacks glass with avidity, while neither sulphuric, nitric, nor muriatic acid has the least effect upon it.
Footnote 22: Hydrofluoric acid is always supplied by chemists in gutta-percha bottles, as it attacks glass.
Place the plate so marked on a white surface, flashed side uppermost, and make a solution of hydrofluoric acid and water, 1 part of the former to 3 of the latter, in a gutta-percha dish or bottle.
But the two processes can hardly have been combined, and the effect is quite unlike that produced when the surface of glass is eaten away by hydrofluoric acid.
By exposing parts of the surface to the fumes of hydrofluoric acid, the only acid that will attack glass.
This is by means of hydrofluoric acid, the only re-agent by which glass is rapidly attacked.
Footnote 212: On the early use of hydrofluoric acid I shall have something to say a little further on.
At a much later periodhydrofluoric acid has been largely employed in England and elsewhere for engraving on glass.
In glass factories if workmen are rendered consumptive by stooping over the grinding machinery, they usually find great benefit by being allowed to work in the room with the glass etchers, where so much hydrofluoric acid is employed.
A french scientist has found that inhalation of air containing a small amount of hydrofluoric acid gas has a remarkably good effect on consumption.
The emery and excess of hydrofluoric acid may then be thrown into a large beaker of clean water and washed several times.
Consequently time may be saved by stirring up the light-coloured mass with a little hydrofluoric acid in a platinum capsule; this dissolves the finely divided glass almost instantaneously.
On October 23 the Laboratory Book says: 'A series of experiments to attempt to decompose hydrofluoric acid, and to ascertain the constitution of the fluoric combinations.
To have done so would have been instant death; the air was a mixture of free fluorine and fluoride gasses, the soil was metallic fluorides, damp with acid rains, and the river was pure hydrofluoric acid.
The hydrogen-fluorine combination is what passes for combustion here; the result is hydrofluoric acid, the local equivalent of water.
This reaction could only take place on a planet receiving lots of ultra-violet because so much energy is needed to break up carbon tetrafluoride and hydrofluoric acid.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "hydrofluoric" in a variety of sentences. We hope that you will now be able to make sentences using this word.
