Chemistry:Antimony tetroxide

Antimony tetroxide

α-Sb 2O 4
β-Sb 2O 4      Sb      O
Names
IUPAC name antimony(III,V) oxide
Identifiers
CAS Number	1332-81-6 Y
PubChem CID	74002
UNII	XB7RVZ5DN5 Y
Properties
Chemical formula	SbO2; Sb2O4
Molar mass	153.7588; 307.5176 g/mol
Appearance	white solid
Density	6.64 g/cm3 (orthorhombic form)
Melting point	> 930 °C (1,710 °F; 1,200 K) (decomposes)
Boiling point	decomposes
Solubility in water	insoluble
Refractive index (nD)	2.0
Structure
Crystal structure	orthorhombic
Hazards
NFPA 704 (fire diamond)	1 2 0
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.5 mg/m3 (as Sb)
REL (Recommended)	TWA 0.5 mg/m3 (as Sb)
Related compounds
Related compounds	Antimony trioxide Antimony pentoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Antimony tetroxide is an inorganic compound with the formula Sb₂O₄. This material, which exists as the mineral cervantite, is white but reversibly yellows upon heating. The material, with empirical formula SbO₂, is called antimony tetroxide to signify the presence of two kinds of Sb centers.

Formation and structure

The material forms when Sb₂O₃ is heated in air:

Sb₂O₃ + 0.5 O₂ → Sb₂O₄ ΔH = −187 kJ/mol

At 800 °C, antimony(V) oxide loses oxygen to give the same material:

Sb₂O₅ → Sb₂O₄ + 0.5 O₂ ΔH = −64 kJ/mol

The material is mixed valence, containing both Sb(V) and Sb(III) centers. Two polymorphs are known, one orthorhombic (shown in the infobox) and one monoclinic. Both forms feature octahedral Sb(V) centers arranged in sheets with distorted Sb(III) centers bound to four oxides.