What is Arsenic trioxide?
[[File:Arsenic trioxide.jpg|thumb|Arsenic trioxide]] '''Arsenic trioxide''', also known as '''white arsenic''', '''arsenic(III) oxide''', '''arsenious oxide''', or {{lang|zh|砒霜}}, is a [[chemical compound]]. Its [[chemical formula]] is As<sub>2</sub>O<sub>3</sub>. It has [[arsenic]] and [[oxide]] [[ion]]s in it. The arsenic is in its +3 [[oxidation state]]. It is very toxic. At very low dose it can be used to treat acute promyelocytic leukemia (APL), a type of blood cancer. ==Properties== Arsenic trioxide is a white [[solid]]. It dissolves in water to make an [[acid]]ic solution of [[arsenious acid]]. It dissolves easily in [[base (chemistry)|bases]] to make [[arsenite]]s. It reacts with concentrated [[hydrochloric acid]] to make [[arsenic trichloride]]. It reacts with very strong [[oxidizing agent]]s to make [[arsenic pentoxide]]. It reacts with [[reducing agent]]s to make arsenic or [[arsine]]. It [[sublime]]s much easier than metal oxides, making it easy to separate by heating the mixture. ==Occurrence and preparation== Arsenic trioxide is rarely found as a [[mineral]]. It is normally made from [[orpiment]] or [[realgar]], arsenic sulfide minerals. About 50,000 tons of arsenic trioxide are made each year. Arsenic trioxide is made by burning arsenic in air, reacting arsenic with concentrated [[sulfuric acid]], or the roasting of [[arsenic sulfide]] ores. ==Safety== Arsenic trioxide is highly toxic when eaten. It also can be toxic if on the skin for long amounts of time. It affects the [[digestive system]] when eaten. Workers exposed to arsenic trioxide fumes in their job can be poisoned as well. ==Uses== It is used to make elemental arsenic. It was used as a pigment (in [[Paris green]]) and as a wood [[preservative]] but was [[ban]]ned in many countries because it is so toxic. === Medical === ==== Treatment of Acute promyelocytic leukemia ==== Arsenic trioxide is used to fight [[acute promyelocytic leukemia]] (APL).<ref name=AHFS2019>{{cite web |title=Arsenic Trioxide Monograph for Professionals |url=https