Copperil) oxide, CujO, occurs naturally as the red cuprite. It is obtained as an orange-yellow precipitate by the reduction of a copper(II) salt in alkaline solution by a mild reducing agent, for example glucose, hydroxylamine or sodium sulphite  [c.414]

Copper occasionally occurs native, and is found in many minerals such as cuprite, malachite, azurite, chalcopyrite, and bornite.  [c.62]

Copper Oxides. Coppet(I) oxide [1317-39-17 is a cubic or octahedral naturally occurring mineral known as cuprite [1308-76-5]. It is ted or reddish brown in color. Commercially prepared coppet(I) oxides vary in color from yellow to orange to ted to purple as particle size increases. Usually coppet(I) oxide is prepared by pytometaHutgical methods. It is prepared by heating copper powder in air above 1030°C or by blending coppet(II) oxide with carbon and heating to 750°C in an inert atmosphere. A particularly air-stable coppet(I) oxide is produced when a stoichiometric blend of coppet(II) oxide and copper powder ate heated to 800—900°C in the absence of oxygen. Lower temperatures can be used if ammonia is added to the gas stream (27-29).  [c.254]

Cryolite, see Sodium hexafluoroaluminate Cryptohalite, see Ammonium hexafluorosilicate Cupric and cuprous, see under Copper Cuprite, see Copper(I) oxide  [c.273]

The iavention of the techniques of melting and casting depended on the development of the technology to produce the requisite high temperatures, which may have been first achieved by potters, ia ca 4000—3500 BC. Coinciding with this discovery was the development of the technique of smelting copper from oxidized ores, eg, cuprite [1308-76-5] CU2O, and malachite [1319-53-5] (copper hydroxy carbonate), Cu2(0H)2C02. Smelting from these ores is easier than the refinement of copper from sulfidic ores, eg, coveUite or chalcopyrite, which iavolves a roasting step iavented ca 2000 years later.  [c.421]

The first iatentional metal ahoy, bronze (ca 3000 Bc), was probably prepared by the smelting of mixed ores, eg, cuprite or malachite for copper and cassiterite for tin (see Tin and tin alloys). However, archeological evidence iadicates that sometime ia the third millenium bc, tin smelting already occurred ia Anatolia (76). The iavention of roasting techniques needed for the refinement of metals from sulfidic ores probably occurred ia the third millenium BC. This discovery enabled the refinement of lead from galena (lead sulfide), and, more importantiy, after the iavention of cupeUation, the separation of silver, present as a significant impurity ia lead prepared from argeatiferous galeaa.  [c.421]

The corrosion processes for various metals are vasdy different, and hence the consequences for the object also differ greatly in nature. For bronze, for example, corrosion starts intergranulady. Cuprite (cuprous oxide) forms as the primary copper corrosion product. Because of the relatively large mobihty of copper ions, a cmst of cuprite forms on the surface and becomes the basis for continued chemical reactions resulting in the formation of products such as malachite and azurite, which are both basic copper carbonates. This corrosion cmst, also known as patina, stabilizes the system to a high degree, slowing the corrosion rate. Because the corrosion progresses slowly, and the copper ions migrate to the surface, the final effect is that the shape of the original surface is preserved, and can be brought to visibiUty through a careful removal of the corrosion cmst. Iron is vastly different. Here, oxides are formed in situ and, because of the enormous increase in specific volume of the corrosion penetrating into the interior, this process leads to serious changes in shape and, ultimately, complete disintegration of the object.  [c.425]

Rot-kali, n. red prussiate of potash (potassium ferricyanide). -kiefer,/. red pine, -klee, m. red clover, -kohl, m. red cabbage, -kohle, /. red charcoal, -kupfer, -kupfererz, n. red copper, red copper ore (cuprite), -lauf, m. erysipelas.  [c.371]

See pages that mention the term Cuprite : [c.111]    [c.118]    [c.265]    [c.265]    [c.192]    [c.366]    [c.58]    [c.75]    [c.1174]    [c.265]    [c.266]    [c.266]   
The Nalco Guide to Cooling Water System Failure Analysis (1993) -- [ c.75 ]

Chemistry of the elements (1998) -- [ c.1174 ]