arsenoxid

Arsenoxid, or arsenic oxide, refers to inorganic compounds composed of arsenic and oxygen. The most common forms are arsenic trioxide (As2O3, arsenious oxide) and arsenic pentoxide (As2O5, arsenic acid anhydride). These solids arise when arsenic-containing minerals are oxidized. As2O3 typically appears as a white to pale yellow powder, while As2O5 is a white, crystalline solid that readily absorbs moisture.

In water, As2O3 hydrolyzes to arsenious acid (H3AsO3); As2O5 hydrolyzes to arsenic acid (H3AsO4). Thus both compounds can act as sources of arsenite and arsenate in solutions. They are relatively stable at ambient conditions but can decompose under certain circumstances.

Production and occurrence: Arsenic oxides are produced industrially as byproducts of smelting and refined mineral processing. In nature, arsenic oxides form by the oxidation of arsenic-bearing sulfide minerals, such as realgar (AsS) and orpiment (As2S3).

Uses: Arsenic trioxide has a range of historical and contemporary applications, including use in glass production, as a reagent in organic synthesis, and in medicine for certain leukemias (notably arsenic trioxide in treating acute promyelocytic leukemia). Arsenic pentoxide is mainly employed as a dehydrating agent and in various chemical syntheses. Because of their toxicity, usage is tightly regulated.

Hazards and safety: Both forms are highly toxic and potentially carcinogenic. Exposure can occur via inhalation of dust or ingestion. Handling requires appropriate personal protective equipment, adequate ventilation, and disposal as hazardous waste.