iron(II) oxide
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Iron(II) oxide or ferrous oxide is the
inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. However, the distinction is not clearly defined; authorities have differing views on the s ...
with the formula FeO. Its mineral form is known as
wüstite Wüstite (Fe O) is a mineral form of iron(II) oxide Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite.https://www.mindat.org/min-4316.htmlhttps://www.ima-mineralogy.org/Minlis ...
. One of several
iron oxide Iron oxides are chemical compounds composed of iron and oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, ...

iron oxide
s, it is a black-colored powder that is sometimes confused with
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic ...

rust
, the latter of which consists of hydrated
iron(III) oxide Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titanium and titanium forms ...
(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.


Preparation

FeO can be prepared by the thermal decomposition of
iron(II) oxalate Ferrous oxalate, or iron(II) oxalate, is an inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composi ...
. :FeC2O4 → FeO + CO2 + CO The procedure is conducted under an inert atmosphere to avoid the formation of
iron(III) oxide Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titanium and titanium forms ...
(Fe2O3). A similar procedure can also be used for the synthesis of
manganous oxide Manganese(II) oxide is an inorganic compound with chemical formula MnO.Arno H. Reidies "Manganese Compounds" Ullmann's Encyclopedia of Chemical Technology 2007; Wiley-VCH, Weinheim. It forms green crystals. The compound is produced on a large sc ...
and
stannous oxide Tin(II) oxide (stannous oxide) is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form. Preparation and reactions Blue- ...
. Stoichiometric FeO can be prepared by heating Fe0.95O with metallic iron at 770 °C and 36 kbar.Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford University Press


Reactions

FeO is thermodynamically unstable below 575 °C, tending to disproportionate to metal and Fe3O4: :4FeO → Fe + Fe3O4


Structure

Iron(II) oxide adopts the cubic,
rock salt Halite ( or ), commonly known as rock salt, is a type of salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a cry ...
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. In contrast to the crystalline solid, in the molten state iron atoms are coordinated by predominantly 4 or 5 oxygen atoms. Below 200 K there is a minor change to the structure which changes the symmetry to rhombohedral and samples become
antiferromagnetic Antiferromagnetic ordering In materials that exhibit antiferromagnetism, the magnetic moment The magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field A magnetic field is a vec ...

antiferromagnetic
.


Occurrence in nature

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.


Uses

Iron(II) oxide is used as a
pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compound , CH4; is among the simplest organic compou ...
. It is
FDA The United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country Contiguous United States, primarily located in North America. It consists of 50 U.S. state, states, a Wash ...
-approved for use in cosmetics and it is used in some
tattoo A tattoo is a form of body modification Body modification (or body alteration) is the deliberate altering of the human anatomy or human physical appearance. It is often done for aesthetics, sexual enhancement, rites of passage, religious s ...

tattoo
inks. It can also be used as a phosphate remover from home aquaria.


See also

*
Iron(II) hydroxide Iron(II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH)2. It is produced when iron(II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide Hydroxide is a polyatomic ion, diatomic anion wi ...
*
Iron(II) In chemistry, iron(II) refers to the chemical element, element iron in its +2 oxidation number, oxidation state. In salt (chemistry), ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe2+. The adjecti ...


References


External links


Wustite Mineral Data
{{oxygen compounds Iron(II) compounds Iron oxide pigments Non-stoichiometric compounds Transition metal oxides Rock salt crystal structure