Copper oxide black

Synonyms cupric oxide copper oxide black... 

Copper (10 oxide Copper (2+) oxide Copper oxide, black. See Copper oxide (ic)... 

CAS 1317-38-0 EINECS/ELINCS 215-269-1 Synonyms Black copper oxide Cl 77403 Copper brown Copper monoxide Copper oxide Copper (II) oxide Copper (2+) oxide Copper oxide, black Cupric oxide Pigment black 15 Empirical CuO... 

When it is desirable to use a weak black, bone black may be substituted for carbon. It is manufactured by calcining animal bones and contains approximately 85% calcium phosphate and calcium carbonate. Black iron oxide (Fe O is stable up to 150°C. Copper chromite black (Cu(Cr02)2) is iuert to all but mbberlike compositions and has been calcined to 600°C. 

A routine inspection of the tube bundle during a plant outage revealed fine cracks of the type shown in Fig. 9.11. Scattered longitudinal cracks were observed along the lengths of most tubes. The external surface was covered with a thin film of black copper oxide and deposits. The bundle had been exposed to ammonia levels that produced 14 ppm of ammonia in the accumulated condensate. 

When present as a minor constituent, iron oxides typically impart a tan to brown color to the overall deposit. When iron oxides are present as a major constituent, the color is red-brown to black. Where iron oxides are found, copper oxides usually are also present (typically at 10-15% of the amount of iron oxide concentration). 

By convention, the chemical formulas of many ionic compounds do not explicitly state the charges of the ions. It is not necessary to do so when the species involved form ions with only one possible charge. However, many metals form more than one type of stable cation. For example, copper forms two different oxides, black CuO and red C112 O. The oxide anion has a -2 charge, so for the first compound to be neutral the copper cation must bear a +2 charge. In C112 O, each copper ion must have +1 charge. 

Pliny mentions other black pigments used for various purposes—bitumen for painting statues and protecting copper vessels 40 burnt ivory (boneblack) and a black obtained by dyers a black inflorescence which adheres to the brazen dye-pans (copper oxide). The saepia also secretes a black liquid, but from this he says no color is prepared. That black oxide of manganese was used by the ancients as a pigment, we know from analyses already referred to, but no clearly recognizable reference to this substance has been identified in the ancient authors. 

It remains to be noted that, when there is no method available for ascertaining the formula weight or a compound, the simplest formula, based on chemical analysis and the use of symbol weighLs of the contained elements, is used, e g., ferric oxide, FejOj, ferroferric oxide, FejCXt, ferrous oxide, FeO, cupric oxide (black copper oxide), CuO. cuprous oxide (red copper oxide). CujO. The customary formula of water is H2O. which is correct ai temperatures above I00°C—actually, liquid water is mainly dihydrol (HjOh. 

Cupric Oxide or Black Copper Oxide, CuO, mw 79.54, blk cubic crysts (Paramelaconite, d 6.40) or blk triclinic crysts (Tenorite, d 6.45)>mP 1026° (decomp) insol in w sol in acids, KCN Amm chloride. Can be prepd by the ignition of cupric carbonate or nitrate (Refs 1-8)... 

Above 75°C, a black precipitant forms in the BCA reaction mixture and the absorbance at 562 nm of the blank increases dramatically. This appeal s to be caused by the formation of copper oxide at high temperature. 

The hydroxides may also contain water of hydration additionally present may be some red-brown hematite (Fe2C>3), gray-black iron carbonate (FeCC>3), plus copper oxide, silicates, etc. 

Since 1982 pennies are made of zinc metal coated with copper metal. Older pennies are made of only copper. The copper atoms on the surface of the penny can combine with oxygen gas in the air. The copper atoms and oxygen molecules combine to form copper oxide. Copper metal is shiny and bright. Copper oxide is brown or black and is not shiny. 

Powdered black copper oxide when stirred into water gives a black suspension and does not visibly dissolve. If the suspension is allowed to stand the black powder settles to the bottom and the clear liquid above contains so few ions of Cu++ and OH that they cannot be detected by the reagents commonly used for detecting these ions, NH4OH, Na2S. Yet we are confronted with the fact that, when acid is added to the suspension of copper oxide, the black powder dissolves completely and we obtain a clear blue solution of the cupric salt. The initial and final substances in this reaction are given in the equation... 

Dilute nitric acid attacks copper, forming copper nitrate, a soluble salt, so that the surface of the metal remains free until the copper has all reacted. Copper oxide may be obtained by heating the solution, first to expel the water, and then with a somewhat stronger heat to decompose the residue of copper nitrate oxides of nitrogen escape as red fumes, and copper oxide remains as a black solid. This is the method by which zinc was converted quantitatively into zinc oxide, page 24. 

---