Caesium oxide It is a good electron emitter; however, its high vapor pressure limits its usefulness. Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product: CsO is hygroscopic, forming the corrosive CsOH on contact with water. Caesium oxide Caesium oxide (IUPAC name) or cesium oxide describes inorganic compounds composed of caesium and oxygen. The following binary (containing only Cs and O) oxides of caesium are known: CsO, CsO, CsO, and CsO. Both the oxide and suboxides are brightly coloured. The species CsO forms yellow-orange hexagonal crystals. Caesium oxide is used in photocathodes to detect infrared signals in
Copper(II) oxide from the solids. These complexes are decomposed with steam to give CuO. It can be formed by heating copper in air at around 300 – 800°C: For laboratory uses, pure copper(II) oxide is better prepared by heating copper(II) nitrate, copper(II) hydroxide or copper(II) carbonate: Copper(II) oxide dissolves in mineral acids such as hydrochloric acid, sulfuric acid or nitric acid to give the corresponding copper(II) salts: It reacts with concentrated alkali to form the corresponding cuprate salts: It can also be reduced to copper metal using hydrogen, carbon monoxide, or carbon: When cupric oxide is substituted for iron oxide in thermite