Sodium dihydrogen arsenate Sodium dihydrogen arsenate Sodium dihydrogen arsenate is the inorganic compound with the formula NaHAsO. Related salts are also called sodium arsenate, including NaHAsO (disodium hydrogen arsenate) and NaHAsO (sodium dihydrogen arsenate). Sodium dihydrogen arsenate is a colorless solid that is highly toxic. The salt is the conjugate base of arsenic acid: In the laboratory, it is prepared in this way, crystallizing from a hot saturated aqueous solution, where it is highly soluble when hot (75.3 g in 100 mL at 100 °C). It is obtained as the monohydrate. Upon heating, solid NaHAsOHO, loses water of crystallization and converts to the
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