Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite.[3][4] One of several iron oxides, it is a black-colored powder that is sometimes confused with rust, the latter of which consists of hydrated iron(III) oxide (ferric oxide). Iron(II) oxide also refers to a family of related non-stoichiometric compounds, which are typically iron deficient with compositions ranging from Fe0.84O to Fe0.95O.[5]
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| Names | |
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| IUPAC name
Iron(II) oxide
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| Other names
Ferrous oxide, Iron monoxide, Wüstite
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.014.292 |
| 13590 | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| FeO | |
| Molar mass | 71.844 g/mol |
| Appearance | black crystals |
| Density | 5.745 g/cm3 |
| Melting point | 1,377 °C (2,511 °F; 1,650 K)[1] |
| Boiling point | 3,414 °C (6,177 °F; 3,687 K) |
| Insoluble | |
| Solubility | insoluble in alkali, alcohol dissolves in acid |
| +7200·10−6 cm3/mol | |
Refractive index (nD)
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2.23 |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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can be combustible under specific conditions[2] |
| NFPA 704 (fire diamond) | |
| 200 °C (392 °F; 473 K) | |
| Safety data sheet (SDS) | ICSC 0793 |
| Related compounds | |
Other anions
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Iron(II) sulfide Iron(II) selenide Iron(II) telluride |
Other cations
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Manganese(II) oxide Cobalt(II) oxide |
| Iron(II,III) oxide Iron(III) oxide | |
Related compounds
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Iron(II) fluoride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
editFeO can be prepared by the thermal decomposition of iron(II) oxalate.
- FeC2O4 → FeO + CO2 + CO
The procedure is conducted under an inert atmosphere to avoid the formation of iron(III) oxide (Fe2O3). A similar procedure can also be used for the synthesis of manganous oxide and stannous oxide.[6][7]
Stoichiometric FeO can be prepared by heating Fe0.95O with metallic iron at 770 °C and 36 kbar.[8]
Reactions
editFeO is thermodynamically unstable below 575 °C, tending to disproportionate to metal and Fe3O4:[5]
- 4FeO → Fe + Fe3O4
Structure
editIron(II) oxide adopts the cubic, rock salt structure, where iron atoms are octahedrally coordinated by oxygen atoms and the oxygen atoms octahedrally coordinated by iron atoms. The non-stoichiometry occurs because of the ease of oxidation of FeII to FeIII effectively replacing a small portion of FeII with two-thirds their number of FeIII, which take up tetrahedral positions in the close packed oxide lattice.[8]
In contrast to the crystalline solid, in the molten state iron atoms are coordinated by predominantly 4 or 5 oxygen atoms.[9]
Below 200 K there is a minor change to the structure which changes the symmetry to rhombohedral and samples become antiferromagnetic.[8][10]
Occurrence in nature
editIron(II) oxide makes up approximately 9% of the Earth's mantle. Within the mantle, it may be electrically conductive, which is a possible explanation for perturbations in Earth's rotation not accounted for by accepted models of the mantle's properties.[11]
Uses
editIron(II) oxide is used as a pigment. It is FDA-approved for use in cosmetics and it is used in some tattoo inks. It can also be used as a phosphate remover from home aquaria.
See also
editReferences
edit- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ^ "Ferric(ous) Oxide, Black" (PDF). art.illinois.edu. Archived from the original (PDF) on 11 May 2019.
- ^ "Wüstite". www.mindat.org.
- ^ "List of Minerals". www.ima-mineralogy.org. March 21, 2011.
- ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ H. Lux "Iron (II) Oxide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1497.
- ^ Practical Chemistry for Advanced Students, Arthur Sutcliffe, 1930 (1949 Ed.), John Murray - London
- ^ a b c Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford University Press ISBN 0-19-855370-6
- ^ Shi, Caijuan; Alderman, Oliver; Tamalonis, Anthony; Weber, Richard; You, Jinglin; Benmore, Chris (2020). "Redox-structure dependence of molten iron oxides". Communications Materials. 1 (1): 80. Bibcode:2020CoMat...1...80S. doi:10.1038/s43246-020-00080-4.
- ^ Proceedings of the 5th Unconventional Resources Technology Conference. Tulsa, OK, USA: American Association of Petroleum Geologists. 2017. doi:10.15530/urtec-2017-2670073. ISBN 978-0-9912144-4-0.
- ^ "Science Jan 2012". Archived from the original on January 24, 2012.