Ferric Oxide

Title: Ferric Oxide
CAS Registry Number: 1309-37-1
Additional Names: Ferric sesquioxide; jeweler's rouge
Molecular Formula: Fe2O3
Molecular Weight: 159.69
Percent Composition: Fe 69.94%, O 30.06%
Literature References: a-Form occurs in nature as the mineral hematite. g-Form occurs in nature as the mineral maghemite; prepd by dehydration of a-FeO(OH): Giovanoli, Brütsch, Chimia 28, 188 (1974). Prepn of a third allomorphic form, e-Fe2O3: Schrader, Büttner, Z. Anorg. Allg. Chem. 320, 220 (1963); Trautmann, Forestier, Compt. Rend. 261, 4423 (1965). Color and appearance of Fe2O3 are dependent upon the size and shape of the particles and the amount of combined water. Preparation and properties: Gmelins, Iron (8th ed.) 59, part B, 63-94 (1932); Baudisch, Hartung, Inorg. Synth. 1, 185 (1939); Ullmanns Encyklopädie der technischen Chemie vol. 6, 421-423 (1955); Bernal et al., Clay Miner. Bull. 4, 15-30 (1959). Toxicology: L. T. Fairhall, Industrial Toxicology (Hafner, New York, 2nd ed., 1969) pp 64-66.
NOTE: The composition of the substance called d-Fe2O3 is actually FeO(OH) (Bernal et al.).
CAUTION: Potential symptoms of overexposure to dust and fumes are benign pneumoconiosis with x-ray shadows indistinguishable from fibrotic pneumoconiosis. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 172.
Use: As pigment for rubber, paints, paper, linoleum, ceramics, glass; in paint for ironwork, ship hulls; as polishing agent for glass, precious metals, diamonds; in electrical resistors and semiconductors; in magnets, magnetic tapes; as catalyst; colloidal solns as stain for polysaccharides.
Ferric Phosphate Ferric Pyrophosphate Ferric Sodium Edetate Ferric Sodium Pyrophosphate Ferric Sulfate

This page is about a red colored oxide of iron. For other uses, see Red iron.
Iron(III) oxide
Sample of iron(III) oxide
Haematite unit cell
CAS number 1309-37-1 YesY
PubChem 518696
ChemSpider 14147 N
UNII 1K09F3G675 YesY
KEGG C19424 N
ChEBI CHEBI:50819 YesY
RTECS number NO7400000
Jmol-3D images Image 1
Molecular formula Fe2O3
Molar mass 159.69 g/mol
Appearance red-brown solid
Odor odorless
Density 5.242 g/cm3, solid
Melting point 1,566 °C; 2,851 °F; 1,839 K (decomposes)
Solubility in water insoluble
Crystal structure rhombohedral
Std molar
entropy So298
90 J·mol−1·K−1[1]
Std enthalpy of
formation ΔfHo298
−826 kJ·mol−1[1]
EU classification not listed
Flash point Non-flammable
Related compounds
Other anions iron(III) fluoride
Other cations manganese(III) oxide, cobalt(III) oxide
Related compounds iron(II) oxide, iron(II,III) oxide
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare, and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of the iron for the steel industry. Fe2O3 is ferromagnetic, dark red, and readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered an ill-defined material, described as hydrated ferric oxide.