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Arsenious Oxide : Preparation, Properties and Uses

Arsenious Oxide is also called Arsenic Trioxide.

Preparation of Arsenious Oxide

Arsenic trioxide is formed when arsenic is heated in air.

4As + 3O2 → 2As2O3

On an industrial scale, it is produced by air-roasting arsenic pyrite.

2FeAsS + 5O2 → As2O3 + Fe2O3 + 2SO2

Arsenious Oxide Physical Properties

It is a white colored toxic solid substance. It is found in amorphous and crystal forms. In crystal form, its crystals are of rhombic and octahedral form.

Arsenic Oxide

Arsenious Oxide Chemical Properties

Reaction with water

It dissolves in water to form arsenious acid.

As2O3 + 3H2O → 2H3AsO3

Reaction with concentrated HCl

It reacts with concentrated HCl to form arsenic chloride.

As2O3 + 6HCl → 3H2O + 2AsCl3

Chemistry Notes

Physics Notes

Biology Notes

Reaction with NaOH

Arsenious oxide is an amphoteric oxide. It reacts with both HCl and NaOH. It reacts with sodium hydroxide to form sodium arsenite (Na3AsO3).

As2O3 + 6NaOH → 3H2O + 2Na3AsO3

Reaction with H2S

A yellow precipitate of arsenic sulfide is obtained when H2S gas is passed through a solution of As2O3.

As2O3 + 3H2S → 3H2O + As2S3

Reducing Properties

It reacts with halogens such as nitric acid, potessium parmagnet, hydrogen peroxide and ozone to form arsenic pentoxide(As2O5).

As2O3 + 2I2 + 2H2O → As2O5 + 4HI

As2O3 + 4HNO3 → As2O5 + 4NO2 + 2H2O

The As2O5 obtained in this reaction dissolves in water to form arsenic acid(H3AsO4).

As2O3 + 3H2O → 2H3AsO4

Chemistry Notes

Physics Notes

Biology Notes

Oxidation Properties

It is itself reduced to arsenic by reacting with reducing agents such as SnCl2 and carbon and oxidizes these substances.

As2O3 + 3SnCl2 + 6HCl → 2As + 3SnCl4 + 3H2O

As2O3 + 3C → 2As + 3CO

Arsenious Oxide Uses

It is used to kill rats and flies.

Used to make medicines.

It is used to keep animal skins safe.

It is used for making glass and paint.

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