Electrolysis of a solution in hydrofluoric acid gives cobaltic fluoride, CoF3.
From the behaviour of substances on electrolysis he assumed that all substances had two components, one bearing a negative charge, the other a positive charge.
Berzelius's investigation of the action of the electric current on salts clearly demonstrated the invaluable assistance that electrolysis could render to the isolator of elements; and the adoption of this method by Sir Humphry Davy for the analysis of the hydrates of the metals of the alkalis and alkaline earths, and the results which he thus achieved, established its potency.
Matthiessen in 1855, who obtained the metal by electrolysis and thoroughly examined it and its compounds.
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.
Transformations of electrical into chemical energy are witnessed in the processes of electrolysis (q.v.; see also Electrochemistry and Electrometallurgy).
Arndt, Ber., 1899, 32, p. 2136); by the oxidation of hydroxylamine (ibid., 1900, 33, p. 30); and by the electrolysis of hydrazine and its salts (E.
Journ., 1811, 8, p. 302), and obtained by the action of chlorine or sodium hypochlorite on ammonium chloride, or by the electrolysis of ammonium chloride solution, is a very volatile yellow oil.
When the passage of an electric current through a substance is accompanied by definite chemical changes which are independent of the heating effects of the current, the process is known as electrolysis, and the substance is called an electrolyte.
During the earliest investigation of the subject it was thought that, since hydrogen and oxygen were usually evolved, the electrolysis of solutions of acids and alkalis was to be regarded as a direct decomposition of water.
Faraday examined also the electrolysis of certain fused salts such as lead chloride and silver chloride.
Thus the hydroxyl mentioned above decomposes into water and oxygen, and the chlorine produced by the electrolysis of a chloride may attack the metal of the anode.
This leads us to examine more closely the part played by water in the electrolysis of aqueous solutions.
In the electrolysis of a concentrated solution of sodium acetate, hydrogen is evolved at the cathode and a mixture of ethane and carbon dioxide at the anode.
The obvious phenomena to be explained by any theory of electrolysis are the liberation of the products of chemical decomposition at the two electrodes while the intervening liquid is unaltered.
These views were applied to the theory of electrolysis by R.
Interchanges must be supposed to go on whether a current passes or not, the function of the electric forces in electrolysis being merely to determine in what direction the parts of the molecules shall work their way through the liquid and to effect actual separation of these parts (or their secondary products) at the electrodes.
The verification of Kohlrausch's theory of ionic velocity verifies also the view of electrolysis which regards the electric current as due to streams of ions moving in opposite directions through the liquid and carrying their opposite electric charges with them.
Clausius extended to electrolysis the chemical ideas which looked on the opposite parts of the molecule as always changing partners independently of any electric force, and regarded the function of the current as merely directive.
Whetham, The Theory of Solution and Electrolysis (Cambridge, 1902); M.
In the article Electrolysis it is shown how the passage of an electric current through a solution containing metallic ions involves the deposition of the metal on the cathode.
Under these conditions electrolysis of the solution in the brush takes place.
Zinc is commonly deposited by electrolysis on iron or steel goods which would ordinarily be "galvanized," but which for any reason may not conveniently be treated by the method of immersion in fused zinc. The zinc cyanide bath may be used for small objects, but for heavy goods the sulphate bath is employed.
Among other subjects at which he subsequently worked were the absorption of gases in blood (1837-1845), the expansion of gases by heat (1841-1844), the vapour pressures of water and various solutions (1844-1854), thermo-electricity (1851), electrolysis (1856), induction of currents (1858-1861), conduction of heat in gases (1860), and polarization of heat (1866-1868).
The formation of lead dioxide by the electrolysis of a lead solution, the anode being a lead plate coated with lead oxide or sulphate and the cathode a lead plate, is the fundamental principle of the storage cell (see Accumulator).
Betts, Lead Refining by Electrolysis (1908); M.
By electrolysis it yields uranium dioxide as a pyrophoric powder, and peruranic hydroxide, U04.2H20, when treated with hydrogen peroxide.
Potassium percarbonate, K 2 C 2 0 6, is obtained in the electrolysis of potassium carbonate at -10 to -15°.
Canvas diaphragms were used to prevent the acid formed by electrolysis at the anode from mixing with the cathode liquor, and so hindering deposition.
13,336 of 1894) a rapidly rotating cathode is used in a chloride solution, a porous partition separating the tank into anode and cathode compartments, and the chlorine generated by electrolysis at the anode being recovered.
In many of these the application of heat is necessary to bring the substances used into the liquid state for the purpose of electrolysis, aqueous solutions being unsuitable.
30) obtained potassium by the electrolysis of a mixture of potassium and calcium chlorides fused over a lamp. There are here foreshadowed two types of electrolytic furnace-operations: (a) those in which external heating maintains the electrolyte in the fused condition, and (b) those in which a currentdensity is applied sufficiently high to develop the heat necessary to effect this object unaided.
But in some cases in which the current is used for electrolysis and for the production of extremely high temperatures, for which the calorific intensity of ordinary fuel is insufficient, the electric furnace is employed with advantage.
The reduction is not due to electrolysis, but to the action of carbon on alumina, a part of the carbon in the charge being consumed and evolved as carbon monoxide gas, which burns at the orifice in the cover so long as reduction is taking place.
Sainte Claire Deville working independently obtained aluminium by the electrolysis of the fused double sodium aluminium chloride.
The present article deals with processes that involve the electrolysis of aqueous solutions, whilst those in which electricity is used in the manufacture of chemical products at furnace temperatures are treated under Electrometallurgy, although, strictly speaking, in some cases (e.g.
For the theory and elemental laws of electro-deposition see Electrolysis; and for the construction and use of electric generators see Dynamo and Battery: Electric. The importance of the subject may be gauged by the fact that all the aluminium, magnesium, sodium, potassium, calcium carbide, carborundum and artificial graphite, now placed on the market, is made by electrical processes, and that the use of such processes for the refining of copper and silver, and in the manufacture of phosphorus, potassium chlorate and bleach, already pressing very heavily on the older non-electrical systems, is every year extending.
The chlorine reacts with the caustic soda, forming sodium hypochlorite, and this in turn, with an excess of chlorine and at higher temperatures, becomes for the most part converted into chlorate, whilst any simultaneous electrolysis of a hydroxide or water and a chloride (so that hydroxyl and chlorine are simultaneously liberated at the anode) also produces oxygen-chlorine compounds direct.
It is obvious that, with suitable methods and apparatus, the electrolysis of alkaline chlorides may be made to yield chlorine, hypochlorites (bleaching liquors), chlorates or caustic alkali, but that great care must be exercised if any of these products is to be obtained pure and with economy.
Pp. 198, 329, 43 8) in connexion with the electrolysis of hydrochloric acid.
Hermite, which consisted in the production of bleach-liquors by the electrolysis (according to the 1st edition of the 1884 patent) of magnesium or calcium chloride between platinum anodes carried in wooden frames, and zinc cathodes.
His system for the disinfection of sewage and similar matter by the electrolysis of chlorides, or of sea-water, has been tried, but for the most part abandoned on the score of expense.
Again, anode reactions, such as are observed in the electrolysis of the fatty acids, may be utilized, as, for example, when the radical CH3C02 - deposited at the anode in the electrolysis of acetic acid - is dissociated, two of the groups react to give one molecule of ethane, C 2 H 6, and two of carbon dioxide.
The production of ozone in small quantities during electrolysis, and by the so-called silent discharge, has long been known, and the Siemens induction tube has been developed for use industrially.
In Berzelius' system + potassium sulphate is to be regarded as K 2 0.S0 3; electrolysis should simply effect the disruption of the positive and negative components, potash passing with the current, and sulphuric acid against the current.
Gold is also attacked when strong sulphuric acid is submitted to electrolysis with a gold positive pole.
Other metals which find application in the metallurgy of gold by virtue of their property of extracting the gold as an alloy are lead, which combines very readily when molten, and which can afterwards be separated by cupellation, and copper, which is separated from the gold by solution in acids or by electrolysis; molten lead also extracts gold from the copper-gold alloys.
Davy, inspired by his successful isolation of the metals sodium and potassium by the electrolysis of their hydrates, attempted to decompose a mixture of lime and mercuric oxide by the electric current; an amalgam of calcium was obtained, but the separation of the mercury was so difficult that even Davy himself was not sure as to whether he had obtained pure metallic calcium.
Filr Electrochemie, 1902, p. 8757) obtained the metal of 90% purity by electrolysing calcium chloride at a temperature of about 780°, using an iron cathode, the anode being the graphite vessel in which the electrolysis was carried out.
On electrolysis a layer of metallic calcium is formed at the lower end of this rod on the surface of the electrolyte; the rod is gradually raised, the thickness of the layer increases, and ultimately a rod of metallic calcium, forming, as it were, a continuation of the iron cathode, is obtained.