Мышьяк (V) оксид

Химические свойства

Arsenic pentoxide is an important commercial compound of arsenic. It is a white, shapeless (amorphous), crystalline, lumpy solid or, hygroscopic powder, and is not combustible. It emits irritating or toxic fumes (or gases) in a fi re. Arsenic pentoxide is used as a solid or as a solution in the manufacture of arsenates, weed killer, metal adhesives, insecticides, fungicide wood preservatives, and colored gases, and in printing and dyeing. It can be synthesized either by burning elemental arsenic in oxygen, or by oxidizing arsenic trioxide with oxidizing agents, such as ozone, hydrogen peroxide, and nitric acid. Arsenic pentoxide decomposes to oxygen and As2O3 on heating, and dissolves readily in water to form arsenic acid, H3AsO4. Arsenic pentoxide reacts violently with bromine pentafl uoride and reducing agents, and attacks many metals in the presence of water or moisture.

Физические свойства

White amorphous solid; deliquescent; density 4.32 g/cm³; melts at 315°C; dissolves slowly in water but is very soluble (230 g/100g at 20°C); also soluble in alcohol.

Вхождение

Arsenic pentoxide is used to make colored glass; in fungicide formulations; in adhesive for metals; in wood preservatives; in dyeing and printing; and to prepare arsenates.

Использование

Arsenic pentoxide (As2O5) is manufactured by adding oxygen to the trioxide form and is used to form many arsenic compounds.

Подготовка

Arsenic pentoxide is prepared by dehydration of crystalline arsenic acid at 200°C or above. The former is made by treating arsenic metal or arsenious oxide with nitric acid. Also, the pentoxide can be prepared by the reaction of arsenic trioxide with oxygen under pressure.

Общее описание

A white crystalline solid. Noncombustible. Corrosive to metals in the presence of moisture. Toxic by ingestion.

Реакции воздуха и воды

Dissolves in water to give solutions of arsenic acid.

Опасность

Confirmed carcinogen.

Угроза здоровью

ARSENIC PENTOXIDE is extremely toxic; the probable oral lethal dose for humans is 5-50 mg/kg, or between 7 drops and 1 teaspoonful for a 150-lb. person. It is irritating to eyes, nose, and throat. Chronic exposure may cause nerve damage to the extremities, alter cellular composition of the blood, and cause structural changes in blood components. There is sufficient evidence that inorganic arsenic compounds are skin and lung carcinogens in humans.

Пожароопасность

Fire may produce irritating or poisonous gases. Reacts with metal and may give off toxic arsine gas. Hazardous polymerization may not occur.

Профиль безопасности

Confirmed human carcinogen. Poison by ingestion and intravenous routes. Experimental reproductive effects. Mutation data reported. Reacts vigorously with Rb2C2. When heated to decomposition it emits toxic fumes of arsenic. See also ARSENIC COMPOUNDS.

Возможный контакт

Arsenic pentoxide is used in production of metal arsenates; as an herbicide, defoliant on cotton; as a chemical intermediate; as an ingredient in wood preservatives; and in glass. Other possible uses are as an insecticide and soil sterilant.

хранилище

Arsenic pentoxide should be kept stored separately from strong bases, reducing substances, food, and feedstuffs and dry and safe area.

Перевозки

UN1559 Arsenic pentoxide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Несовместимости

Decomposes above 315 C, forming oxygen and arsenic trioxide fumes. Arsenic pentoxide is an oxidizer; reacts violently with bromine pentafluoride and reducing agents. The solution in water is a weak acid. Incompatible with acids, strong alkalis; halogens, rubidium carbide, zinc. Corrosive to metals in the presence of moisture. Contact with acids or acid mists releases deadly arsine gas.

Утилизация отходов

Dissolve in a minimum of concentrated hydrochloric acid. Dilute with water until white precipitate forms. Add HCl to dissolve. Saturate with H2S; filter and wash precipitate and return to supplier. Alternatively, precipitate with heavy metals, such as lime or ferric hydroxide in lieu of H2S. If needed, seek professional environmental engineering assistance from the United States Environmental Protection Agency Environmental Response Team at (908) 548-8730 (24-hour response line). Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/ mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.

Меры предосторожности

During handling and use of arsenic pentoxide, occupational workers should use protective gloves, protective clothing, safety goggles or eye protection in combination with breathing protection if using powder, and workers should not eat, drink, or smoke in the area. The worker should NOT wash away the spillage/waste into the sewer. The containers of arsenic pentoxide may explode when heated