It reduces many metallic oxides, such as lead monoxide and cupric oxide, and decomposes water at a red heat.
Another mode of separating the two acids is to convert them into calcium salts, which are then treated with a perfectly neutral solution of cupric chloride, soluble cupric citrate and calcium chloride being formed, while cupric tartrate remains undissolved.
Oils which contain sulphur-compounds are subjected to a special process of refining in which cupric oxide or litharge is employed as a desulphurizing agent.
After having previously roasted the tube and copper oxide, and reduced the copper spiral a, the weighed calcium chloride tube and potash bulbs are put in position, the boat containing the substance is inserted (in the case of a difficultly combustible substance it is desirable to mix it with cupric oxide or lead chromate), the copper spiral (d) replaced, and the air and oxygen supply connected up. The apparatus is then tested for leaks.
Among the analytical methods worked up by him the best known is that for the estimation of sugars by "Fehling's solution," which consists of a solution of cupric sulphate mixed with alkali and potassium-sodium tartrate (Rochelle salt).
They may also be prepared by the action of mercuric or cupric oxides on alkaline solutions of hydroxylamine (A.
Thus cupric chloride dissolves in much water with an evolution of heat, but when the solution is nearly saturated, it is cooled by taking up more of the solid.
The only substance which possesses sufficiently strong catalytic properties for the reaction is cupric chloride.
Ferrous chloride decomposes the copper oxide and carbonate with the formation of cuprous and cupric chlorides (which remain in solution), and the precipitation of ferrous oxide, carbon dioxide being simultaneously liberated from the carbonate.
The precipitation of the copper from the solution, in which it is present as sulphate, or as cuprous and cupric chlorides, is generally effected by metallic iron.
Copper sulphide may be converted either into the sulphate, which is soluble in water; the oxide, soluble in sulphuric or hydrochloric acid; cupric chloride, soluble in water; or cuprous chloride, which is soluble in solutions of metallic chlorides.
The bulk of the copper is thus transformed into cupric chloride, little cuprous chloride being obtained.
The most important are cuprous oxide, Cu 2 0, and cupric oxide, CuO, both of Oxides which give rise to well-defined series of salts.
Cuprous oxide is reduced by hydrogen, carbon monoxide, charcoal, or iron, to the metal; it dissolves in hydrochloric acid forming cuprous chloride, and in other mineral acids to form cupric salts, with the separation of copper.
Cupric oxide, CuO, occurs in nature as the mineral melaconite (q.v.), and can be obtained as a hygroscopic black powder by the gentle ignition of copper nitrate, carbonate or hydroxide; also by heating the hydroxide.
Cupric hydroxide, Cu(OH) 2, is obtained as a greenish-blue flocculent precipitate by mixing cold solutions of potash and a cupric salt.
The salts derived from cupric oxide are generally white when anhydrous, but blue or green when hydrated.
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.
Copper dioxide, CuO 2 H 2 O, is obtained as a yellowish-brown powder, by treating cupric hydrate with hydrogen peroxide.
Merrill, it decomposes when heated, and gives cupric hydride, CuH 21 as a reddish-brown spongy mass, which turns to a chocolate colour on exposure.
Cupric fluoride, CuF 2, is obtained by dissolving cupric oxide in hydrofluoric acid.
It is also obtained by burning the metal in chlorine, by heating copper and cupric oxide with hydrochloric acid, or copper and cupric chloride with hydrochloric acid.
Cupric chloride, CuC1 2, is obtained by burning copper in an excess of chlorine, or by heating the hydrated chloride, obtained by dissolving the metal or cupric oxide in an excess of hydrochloric acid.
The oxychloride Cu 3 0 2 C1 2.4H 2 O is obtained as a pale blue precipitate when potash is added to an excess of cupric chloride.
Cuprous iodide, Cu 2 l 21 is obtained as a white powder, which suffers little alteration on exposure, by the direct union of its components or by mixing solutions of cuprous chloride in hydrochloric acid and potassium iodide; or, with liberation of iodine, by adding potassium iodide to a cupric salt.
Cupric iodide is only known in combination, as in Cu12, 4NH 31 H 2 O, which is obtained by exposing Cu 2 I 2, 4NH 3 to moist air.
(See above, Metallurgy.) Cupric sulphide, CuS, occurs in nature as the mineral covellite.
Cu2S5, Cu 2 S 6, Cu4S5, Cu 2 S 3, have been described; they are all unstable, decomposing into cupric sulphide and sulphur.
A cuproso-cupric sulphite, Cu2S03, CuSO 3, 2H 2 0, is obtained by mixing solutions of cupric sulphate and acid sodium sulphite.
Cupric sulphate or " Blue Vitriol," CuSO 4, is one of the most important salts of copper.
Cupric sulphate is obtained commercially by the I 91,000 96,000 1 35, 000 218,400 291,000 900,000 oxidation of sulphuretted copper ores (see above, Metallurgy; wet methods), or by dissolving cupric oxide in sulphuric acid.
Copper sulphate is readily soluble in water, but insoluble in alcohol; it dissolves in hydrochloric acid with a considerable fall in temperature, cupric chloride being formed.
It decomposes when heated to 900; with water it gives nitric oxide and cupric nitrate and nitrite.
Cupric nitrate, Cu(NO 3) 2, is obtained by dissolving the metal or oxide in nitric acid.
The phosphide obtained by heating cupric phosphate, Cu 2 H 2 P 2 O 81 in hydrogen, when mixed with potassium and cuprous sulphides or levigated coke, constitutes " Abel's fuse," which is used as a primer.
Soc., 1906, 3, p. 39.) Cupric phosphate, Cu 3 (PO 4) 2, may be obtained by precipitating a copper solution with sodium phosphate.
Copper arsenate is similar to cupric phosphate, and the resemblance is to be observed in the naturally occurring copper arsenates, which are generally isomorphous with the corresponding phosphates.
Scheele's green is a basic copper arsenite; Schweinfurt green, an aceto-arsenite; and Casselmann's green a compound of cupric sulphate with potassium or sodium acetate.
Normal cupric carbonate, CuCO 3, has not been definitely obtained, basic hydrated forms being formed when an alkaline carbonate is added to a cupric salt.
When potassium iodide is added to a solution of cupric acetate, the reaction (Cu(C 2 H 3 0 2) 2 + 2KI= Cul + 2K(C 2 H 3 0 2) + I takes place; that is, for each atom of copper one atom of iodine is liberated.
This is imperfectly accomplished, in the wet way, by cupric and cuprous chloride solutions, but completely so, in the dry way, by roasting with salt (chloridizing roasting).
When salt and copper sulphate are added to the charge, they form sodium sulphate and cupric chloride, both of which are readily soluble in water.
Cupric chloride acts upon argentite (Ag2S+ CuC1 2 =2AgC1+CuS), proustite (4Ag 3 AsS 3 +4CuC1 2 =8AgC1-}- 2Ag 2 S+4CuS+2As 2 S 3), pyrargyrite (2Ag 3 SbS 3 -I-3CuC1 2 =6AgC1+ 3CuS+Sb 2 S 3), and is also reduced to cuprous chloride by metallic iron.
This salt, insoluble in water but soluble in brine, also acts upon argentite (Ag 2 S-+-Cu 2 C1 2 =2AgC1±-CuS±-Cu) and pyrargyrite (2Ag 3 SbS 3 -I-Cu 2 C12 = 2AgC1 +Ag 2 S +2Ag +2CuS +Sb2S3), and would give with silver sulphide in the presence of quicksilver, the Patioreaction; metallic silver, cupric sulphide, and mercurous chloride (2Ag 2 S+Cu 2 C1 2 +2Hg=4Ag+2CuS+Hg 2 C1 2), but the iron decomposes the quicksilver salt, setting free the quicksilver.
The rationale of the process is that the sulphite hardly acts upon the dissolved oxide of silver, but it reduces some of the cupric oxide to cuprous oxide, which reduces its equivalent of silver oxide to silver and reforming cupric oxide which passes through the same cycle.