A text-book of chemistry by unknow

Author:unknow
Language: eng
Format: epub
Tags: Chemistry, Pharmaceutical chemistry
Publisher: Philadelphia [etc.] J. B. Lippincott company
Published: 1898-03-25T05:00:00+00:00

Copper forms two classes of compounds, one the " ous" in which Cu deports itself as a monad, while in the ''ic" it is a dyad. The cuprous salts are insoluble in water and the Cu ion is colorless. The more important cupric compounds are usually soluble, imparting to water a ^reen or blue color, while the anhydrous salts are colorless. The Cu " ic " iori is blue.

Cuprous Chloride, CuCl, or Cu,Cl„ is formed by dissolving cuprous oxide in hydrochloric acid, taking care to exclude air. It is probably most readily prepared by boiling cupric chloride with copper tumingfs, with the addition of a little platinic chloride to establish galvanic action. On pouring the clear solution into water, which has been heated to expel air, cuprous chloride separates as a white precipitate.

Properties.—Cuprous chloride is a white, crystalline powder, soluble in solution of ammonia, forming a colorless solution which becomes blue on absorption of oxygen from the air. Cuprous chloride may be recrystallized from hot. concentrated hydrochloric acid; it is insoluble in water^ but, left in contact with air, the solution takes on a green color, due to the formation of copper oxychloride.

Digitized by VjOOQIC

On the application of heat, cuprous chloride melts at 430°, and on cooling it forms a solid crystalline mass. Near 1000** it is volatilized.

The solution of cuprous chloride in hydrochloric acid and in ammonia readily absorbs carbon monoxide and a number of compounds of the acetylene series; it is, therefore, a valuable reagent in gas analysis.

Cupric Chloride, CuClj^H,0, is prepared by dissolving i part of cupric oxide in 4 parts of 25 per cent, hydrochloric acid. The solution is filtered, concentrated on a water-bath, and crystallized.

Properties.— Cupric chloride occurs in blue, rhombic crystals, which deliquesce on exposure to damp air. It is readily soluble in water and in alcohol, and somewhat soluble in ether. The aqueous solution of the salt is green when concentrated, since there is only a very slight dissociation, and blue when dilute, owing to presence of blue Cu" ions.

At 100^ the crystals begin to lose their water of cr3rstallization, and at 500** the salt melts; when heated to redness it is decomposed into cuprous chloride and chlorine.

The anhydrous cupric chloride, which is yellow, readily absorbs ammonia, a blue powder having the composition CuCU,6nH» being formed. The solution of the salt in strong aqueous ammonia deposits octahedral crystals of the composition CuCla4NHa.H,0. Both of the above compounds are changed at 150* into a green powder, having the composition CuCl,,2NH«.

When cupric chloride solution is digested with cupric hydroxide, or when potassium hydroxide is added to a cupric chloride solution, there is formed an oxychloride having the composition CuClj.3Cu0.4H,0, and known as atacamite.

Cuprous Bromide, CuBr, and Cupric Bromide, CuBr„ are prepared like the corresponding chlorides, and resemble them in appearance and properties. The anhydrous cupric bromide occurs in lustrous crystals resembling iodine.

Cuprous Iodide, Cul, is the only stable compound of copper and iodine; it is a white, permanent, insoluble powder, which is prepared by adding

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