Antimony trioxide

Antimony trioxide
General
Other names	Antimony(III) oxide Antimony sesquioxide Antimonous oxide
Molecular formula	Sb₂O₃
Molar mass	291.52 g/mol
Appearance	white solid
CAS number	^*
Properties
Density and phase	5.2 g/cm³, α-form
Solubility in water	1.4 mg/100 ml (30 °C)
Melting point	656 °C
Boiling point	1425 °C
Acidity (pK_a)	?
Basicity (pK_b)	?
Structure
Coordination geometry	?
Crystal structure	cubic (α) <570 °C orthorhombic (β) >570 °C
Dipole moment	zero
Thermodynamic data
Std enthalpy of formation Δ_fH^o₂₉₈	? kJ/mol
Standard molar entropy S^o₂₉₈	? J·K⁻¹·mol⁻¹
Hazards
MSDS	External MSDS
EU classification	Harmful (Xn) Carc. Cat. 3
R-phrases
S-phrases	, ,
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	Antimony trisulfide
Other cations	Arsenic trioxide Bismuth trioxide
Related compounds	Diantimony tetraoxide Antimony pentoxide
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Chemical infobox

Antimony trioxide is the most important commercial compound of antimony.

Preparation

Burning elemental antimony in air
Roasting antimonide minerals (main industrial route)

Chemical properties

Antimony trioxide is an amphoteric oxide, dissolving in alkaline solution to give antimonites and in acid solution to given a range of polyantimonous acids. It can be readily oxidized to antimony pentoxide or other antimony(V) compounds, but is also easily reduced to antimony, sometimes with production of stibine.

Uses

The annual consumption of antimony trioxide in the United States is approximately 10000 tonnes.

Flame retardant for textiles and polymers
Opacifying agent for glasses, ceramics and enamels
Pigment

Toxicology

Antimony trioxide is only weakly absorbed by the digestive system, and the main route of exposure is by inhalation of the dust. The elimination of antimony from the body is slow, leading to a risk of chronic toxicity. Acute poisoning is rare, and the signs are fairly non-characteristic (vomiting, abdominal pain, irritation of the mucous membranes, diarrhea, cardiac irregularities).

Chronic poisoning by antimony trioxide is sometimes found in exposed workers. The main signs are irritation of the respiratory tract and of the skin and a characteristic pneumoconosis which is visible on chest X-rays.

Antimony trioxide is known to pass into breast milk and to transverse the placenta. Exposed female worker have a higher incidence than usual of menstrual problems and of late-term miscarriages; their children develop slower than usual during the first twelve months of life.

Bibliography

Institut national de recherche et de sécurité (INRS), Fiche toxicologique nº 198 : Trioxyde de diantimoine, 1992.

External links

Antimony compounds | Oxides