Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite. 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.
Ferrous oxide,iron monoxide
3D model (JSmol)
|Molar mass||71.844 g/mol|
|Melting point||1,377 °C (2,511 °F; 1,650 K)|
|Boiling point||3,414 °C (6,177 °F; 3,687 K)|
|Solubility||insoluble in alkali, alcohol |
dissolves in acid
Refractive index (nD)
|Main hazards||can be pyrophoric|
|Safety data sheet||ICSC 0793|
|iron(II) fluoride, iron(II) sulfide, iron(II) selenide, iron(II) telluride|
|manganese(II) oxide, cobalt(II) oxide|
|Iron(III) oxide, Iron(II,III) oxide|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
FeO can be prepared by the thermal decomposition of iron(II) oxalate.
- FeC2O4 → FeO + CO2 + CO
Stoichiometric FeO can be prepared by heating Fe0.95O with metallic iron at 770 °C and 36 kbar.
- 4FeO → Fe + Fe3O4
Iron(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.
Occurrence in natureEdit
Iron(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.
Iron dissolved in groundwater is in the reduced iron II form. If this groundwater comes in contact with oxygen at the surface, e.g. in natural springs, iron II is oxidised to iron III and forms insoluble hydroxides in water.
- Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
- 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
- Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford University Press ISBN 0-19-855370-6
- Science Jan 2012 Archived January 24, 2012, at the Wayback Machine