Cupric arsenate

Cupric arsenate, Cu3(As04)2.—The arsenate occurs as pentahydrate under the name trichalcite. The tetrdhydrate is produced by heating cupric nitrate with calcium arsenate, or copper with a solution of arsenic acid,1 and also by the interaction of cupric chloride and silver arsenate.2 Concentration at 70° C. of a solution of cupric carbonate in excess of arsenic acid yields pale-blue leaflets of the formula CuHAsO 4,H20.3 Other acidic salts,4 and also basic salts,5 are known. 

In REACT, we prepare the calculation by disenabling the redox couple between trivalent and pentavalent arsenic (arsenite and arsenate, respectively). As well, we disenable the couples for ferric iron and cupric copper, since we will not consider either ferrous or cupric species. We load dataset FeOH+.dat , which contains the reactions from the Dzombak and Morel (1990) surface complexation model, including those for which binding constants have only been estimated. The procedure is... 

The reaction with salts of mercury is similar, but with mercuric salts a precipitate of the mercurous salt first appears, which gradually disappears, leaving a deposit of mercury. The arsenic passes into solution as the trioxide. Similarly, copper is deposited from solutions of its common salts with cupric chloride some cuprous chloride is precipitated. The reactions generally are incomplete. 

Copper Arsenates.—Cupric orthoarsenate, Cu3(As04)2, is formed when metallic copper is heated at 180° to 200° C. with aqueous arsenic acid in a sealed tube after some hours the product consists of green triclinie crystals of the arsenate mixed with arsenious oxide and unchanged copper.12 The tetrahydrate, Cu3(As04)2.4H20, is produced by heating cupric nitrate solution with calcium arsenate,13 by the interaction... 

Copper Thioarsenates.—Cupric Orthothioarsenate, Cu3(AsS4)2, is formed as a dark brown precipitate when sodium orthothioarsenate is added to a solution of a cupric salt.2 The reaction, however, is complex, sulphides of copper and arsenic also being formed.3 A similar precipitate is formed when ammonium hydrosulphide or hydrogen sulphide is added to a solution of arsenic acid and a copper salt,4 and the proportion of sulphide and thio-salt in the precipitate varies with the concentration of the reactants. Copper hydroxide reacts with alkali thioarsenates to form copper sulphide and alkali arsenate, but some copper orthothioarsenate is formed and remains in solution in excess of alkali thioarsenate.5... 

NH3.H20 mw 245.8, dk blue cryst pdr. This compd,known since 1693 (Ref 3), can be prepd by dissolving cupric sulfate in Amm hydroxide and precipating with ale. Used in manuf of Cu arsenate, insecticides treating fiber products Refs 1) Mellor 3(1923), 253 (Monohydrated cupric tetrammino sulfate 2) Sax (1957), 502 (Called Copper ammonium sulfate) 3) Gmelin,... 

Occluded hydrogen is more reactive chemically than the normal gas. Hydrogenated palladium precipitates mercury and mercurous chloride from an aqueous solution of the dichloride, without any evolution of hydrogen. It reduces ferric salts to ferrous potassium ferricyanide to ferrocyanide chlorine water to hydrochloric add iodine water to hydriodic acid 2 chromates to chromic salts ceric to cerous salts whilst cupric, stannic, arsenic, manganic, vanadic, and molybdic compounds are also partially reduced.3... 

The pan-amalgamation process has found more favour than the patio process. The ore in the form of fine sludge is stirred in iron pans with a mixture of mercury, common salt, and cupric sulphate. When the action is complete, the excess of mercury is drained off, and the amalgam is allowed to settle, and then decomposed by heat. In the Boss system the process is continuous, a series of pans and settlers being employed. Some silver ores, notably those containing sulphides of arsenic, antimony, copper, iron, and zinc, are roasted with common salt before amalgamation. 

The Ziervogel process can be worked with argentiferous copper mattes free from lead, arsenic, antimony, and bismuth. By roasting the matte in an oxidizing atmosphere, the iron is converted into sulphate. About 700° C. this substance is decomposed, the copper being converted into sulphate. At 840° to 850° C. the copper salt is converted into cupric oxide,8 and silver sulphate simultaneously formed. At this point the roasting is stopped, the silver sulphate is extracted with hot water, and the silver precipitated by means of metallic copper. These mattes are now usually worked for copper, and the silver separated electrolytically. 

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