|Molar mass||70.9374 g/mol|
|Appearance||green crystals or powder|
|Melting point||1,945 °C (3,533 °F; 2,218 K)|
|Solubility in water||insoluble|
|Solubility||soluble in acid|
|Refractive index (nD)||2.16|
|Crystal structure||Halite (cubic), cF8|
|Space group||Fm3m, No. 225|
|Octahedral (Mn2+); octahedral (O2–)|
|Std enthalpy of
|EU Index||Not listed|
|Other anions||Manganese difluoride
|Other cations||Iron(II) oxide|
|Related manganese oxides||Manganese(II,III) oxide
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Manganese(II) oxide (systematically named manganese(2+) oxide(2−)) is an inorganic compound with chemical formula MnO. It forms green crystals. The compound is produced on a large scale as a component of fertilizers and food additives.
Structure, stoichiometry, reactivity
Like many monoxides, MnO adopts the rock salt structure, where cations and anions are both octahedrally coordinated. Also like many oxides, manganese(II) oxide is often nonstoichiometric: its composition can vary from MnO to MnO1.045.
Below 118 K MnO is antiferromagnetic. MnO has the distinction of being one of the first compounds to have its magnetic structure determined by neutron diffraction, the report appearing in 1951. 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 the chemical reactions typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt and water. Oxidation of manganese(II) oxide gives manganese(III) oxide.
Preparation and occurrence
- MnO2 + H2 → MnO + H2O
- MnO2 + CO → MnO + CO2
MnO can also be prepared by decarbonation of the carbonate:
- MnCO3 → MnO + CO2
An alternative route, mostly for demonstration purposes, is the oxalate method, also applicable to the synthesis of ferrous oxide and stannous oxide. Upon heating in an oxygen-free atmosphere (usually CO2), manganese(II) oxalate decomposes into MnO:
- MnC2O4·2H2O → MnO + CO2 + CO + 2 H2O
Together with manganese sulfate, MnO is a component of fertilizers and food additives. Many thousands of tons are consumed annually for this purpose. Other uses include: a catalyst in the manufacture of allyl alcohol, ceramics, paints, colored glass, bleaching tallow and textile printing.
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- Arno H. Reidies "Manganese Compounds" Ullmann's Encyclopedia of Chemical Technology 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_123
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