Properties Molecular formula: CuO Molar mass: 79.545 g/mol Appearance: Black to brown powder Density: 6.315 g/cm3 Melting point: 1326 ° C, 1599 K, 2419 ° F Boiling point: 2000 ° C, 2273 K, 3632 ° F Solubility in waterinsoluble Solubilitysoluble in ammonium chloride Insoluble in alcohol, ammonium hydroxide, ammonium carbonate Band gap: 1.2 eV Refractive index: (ND)2.63
Cupric oxide is used as a pigment in ceramics to produce blue, red, and green (and sometimes gray, pink, or black) glazes. It is also used to produce cuprammonium hydroxide solutions, used to make rayon. It is also occasionally used as a dietary supplement in animals, against copper deficiency. Copper(II) oxide has application as a p-type semiconductor, because it has a narrow band gap of 1.2 eV. It is an abrasive used to Polish optical equipment. Cupric oxide can be used to produce dry cell batteries. It has also been used in wet cell batteries as the cathode, with lithium as an anode, and dioxalane mixed with lithium perchlorate as the electrolyte. Copper(II) oxide can be used to produce other copper salts. It is also used when welding with copper alloys.
Another use for cupric oxide is as a substitute for iron oxide in thermite. This can turn the thermite from an incendiary to a low explosive.