| 83rd | Top inorganic compounds |
| Iron(II) oxide | |
|---|---|
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| IUPAC name |
Iron(II)
oxide
|
| Other names | Ferrous oxide |
| Identifiers | |
| CAS number | 1345-25-1  |
| PubChem | 14945 |
| Properties | |
| Molecular formula | FeO |
| Molar mass | 71.844 g/mol |
| Appearance | black crystals |
| Density | 5.745 g/cm3 |
| Melting point |
1377 °C, 1650 K, 2511 °F ([1]) |
| Boiling point |
3414 °C, 3687 K, 6177 °F |
| Solubility in water | Insoluble |
| Solubility | insoluble in alkali, dissolves in acid |
| Hazards | |
| MSDS | ICSC 0793 |
| EU Index | Not listed |
| Main hazards | can be pyrophoric |
| Autoignition temperature |
variable |
| Related compounds | |
| Other anions | iron(II) fluoride, iron(II) sulfide, iron(II) selenide, iron(II) telluride |
| Other cations | manganese(II) oxide, cobalt(II) oxide |
| Related compounds | Iron(III) oxide, Iron(II,III) oxide |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Iron(II) oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted iron, is one of the iron oxides. It is a black-colored powder with the chemical formula FeO. It consists of the chemical element iron in the oxidation state of 2 bonded to oxygen. Its mineral form is known as wüstite. Iron(II) oxide should not be confused with rust, which usually consists of hydrated iron(III) oxide (ferric oxide). Iron(II) oxide is an example of a non-stoichiometric compound and the ratio of the elements iron and oxygen can vary, samples are typically iron deficient with a compositions ranging from Fe0.84O to Fe0.95O.[2]
Contents |
FeO can be prepared by heating iron(II) oxalate in vacuo:[2]
The black powder can be made less reactive by heating. The heated sample has a more physical change is quenched to prevent disproportionation.[3] Stoichiometric FeO can be prepared by heating Fe0.95O with metallic iron at 770 °C and 36 kbar.[4]
FeO is thermodynamically unstable below 575 °C, disproportionating to metal and Fe3O4:[2]
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.[4]
Below 200 K there is a minor change to the structure which changes the symmetry to rhombohedral and samples become antiferromagnetic.[4]
Iron(II) oxide is used as a pigment. It is FDA-approved for use in cosmetics and it is used in some tattoo inks.
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Iron(II) oxide is an chemical compound composed of iron in the +2 oxidation state bonded to oxygen atoms. It easily converts to a mixture of iron and iron(III) oxide at room temperature. It is stable though when it is very hot. It is a black powder. If it gets hydrated (bonded to extra water molecules), it turns green. The green chemical, named iron(II) hydroxide, gets oxidized by oxygen to a reddish color of iron(III) oxide.
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