-oxide-xtal-3D-SF.png) | |
| Names | |
|---|---|
| IUPAC name Manganese(II) oxide | |
| Other names | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.014.269 |
| EC Number |
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| RTECS number |
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| UNII | |
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| Properties | |
| MnO | |
| Molar mass | 70.9374 g/mol |
| Appearance | green crystals or powder |
| Density | 5.43 g/cm3 |
| Melting point | 1,945 °C (3,533 °F; 2,218 K) |
| insoluble | |
| Solubility | soluble in acid |
| +4850.0·10−6 cm3/mol | |
Refractive index (nD) | 2.16 |
| Structure | |
| Halite (cubic),cF8 | |
| Fm3m, No. 225 | |
| Octahedral (Mn2+); octahedral (O2−) | |
| Thermochemistry | |
Std molar entropy(S⦵298) | 60 J·mol−1·K−1[1] |
Std enthalpy of formation(ΔfH⦵298) | −385 kJ·mol−1[1] |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Otheranions | Manganese(II) fluoride Manganese(II) sulfide Manganese(II) selenide Manganese(II) telluride |
Othercations | Iron(II) oxide |
| Manganese(II,III) oxide Manganese(III) oxide Manganese dioxide Manganese heptoxide | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Manganese(II) oxide is aninorganic compound withchemical formula MnO.[2] It forms green crystals. The compound is produced on a large scale as a component offertilizers andfood additives.
Like many metal monoxides, MnO adopts therock salt structure, where cations and anions are both octahedrally coordinated. Also like many metal oxides, manganese(II) oxide is oftennonstoichiometric: its composition can vary from MnO to MnO1.045.[3]
Below 118 K, MnO isantiferromagnetic.[3] MnO has the distinction of being one of the first compounds[4] to have its magnetic structure determined byneutron diffraction, the report appearing in 1951.[5] This study showed that the Mn2+ ions form a face centered cubic magnetic sub-lattice where there are ferromagnetically coupled sheets that are anti-parallel with adjacent sheets.
Manganese(II) oxide undergoes thechemical reactions typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt.[3] Oxidation of manganese(II) oxide givesmanganese(III) oxide.
MnO occurs in nature as the rare mineralmanganosite.
It is prepared commercially by reduction of MnO2 withhydrogen,carbon monoxide ormethane, e.g.:[2]
Upon heating to 450 °C,manganese(II) nitrate gives a mixture of oxides, denoted MnO2−x, which can be reduced to the monoxide with hydrogen at ≥750 °C.[6]MnO is particularly stable and resists further reduction.[7]MnO can also be prepared by heating the carbonate:[8]
Thiscalcining process is conducted anaerobically, lestMn2O3 form.
An alternative route, most interest for demonstration purposes, is the "oxalate method". Also applicable to the synthesis offerrous oxide andstannous oxide, it entails heating in an oxygen-free atmosphere (often CO2), hydratedmanganese(II) oxalate:[9]
Together withmanganese sulfate, MnO is a component offertilizers and food additives. Many thousands of tons are consumed annually for this purpose. Other uses include: acatalyst in the manufacture ofallyl alcohol, ceramics, paints, colored glass, bleaching tallow and textile printing.[2]
