Antimony tetroxide

Antimony tetroxide

Sb      O
Names
IUPAC name antimony(III,V) oxide
Identifiers
CAS Number	1332-81-6 N
ECHA InfoCard	100.032.554
PubChem	74002
Properties
Chemical formula	SbO2; Sb2O4
Molar mass	153.7588; 307.5176 g/mol
Appearance	white solid
Density	6.64 g/cm3 (orthorhombic form) [1]
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	1 2 0
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 0.5 mg/m3 (as Sb)[2]
REL (Recommended)	TWA 0.5 mg/m3 (as Sb)[2]
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,^[3] 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:^[4]

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.^[1] Both forms feature octahedral Sb(V) centers arranged in sheets with distorted Sb(III) centers bound to four oxides.

References

1. 1 2 Amador, J.; Puebla, E. Gutierrez; Monge, M. A.; Rasines, I.; Valero, C. Ruiz (1988). "Diantimony Tetraoxides Revisited". Inorganic Chemistry. 27: 1367–1370. doi:10.1021/ic00281a011. 
2. 1 2 "NIOSH Pocket Guide to Chemical Hazards #0036". National Institute for Occupational Safety and Health (NIOSH). 
3. ↑ "Cervantite". Webminerals. Retrieved 2009-06-06. 
4. ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.