Manganese(II) oxide is an inorganic compound with

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

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 scale as a component of

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

s and

food additives Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (sal ...

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 MnO_1.045. Below 118 K MnO is

antiferromagnetic In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions. ...

. MnO has the distinction of being one of the first compounds to have its magnetic structure determined by

neutron diffraction Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to o ...

, 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 reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

s typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt and

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

. Oxidation of manganese(II) oxide gives manganese(III) oxide.

Preparation and occurrence

MnO occurs in nature as the rare mineral

manganosite Manganosite is a rare mineral composed of manganese(II) oxide MnO. It was first described in 1817 for an occurrence in the Harz Mountains, Saxony-Anhalt, Germany. It has also been reported from Langban and Nordmark, Sweden and at Franklin Furna ...

.
It is prepared commercially by reduction of MnO₂ with

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

, e.g.: :MnO₂ + H₂ → MnO + H₂O :MnO₂ + CO → MnO + CO₂ Upon heating to 450°C,

manganese(II) nitrate Manganese(II) nitrate refers to the inorganic compounds with formula Mn( NO3)2·(H2O)n. These compounds are nitrate salts containing varying amounts of water. A common derivative is the tetrahydrate, Mn(NO3)2·4H2O, but mono- and hexahydrates are ...

gives a mixture of oxides, MnO_2-x, which can be reduced to the monoxide with hydrogen at ≥750°C. MnO is particular stable and resists further reduction. MnO can also be prepared by heating the carbonate: :MnCO₃ → MnO + CO₂ This

calcining Calcination refers to thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), gener ...

process is conducted anaerobically, lest Mn₂O₃ form. An alternative route, mostly for demonstration purposes, is the oxalate method, which also applicable to the synthesis of

ferrous oxide 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 ...

and stannous oxide. Upon heating in an oxygen-free atmosphere (usually CO₂), manganese(II) oxalate decomposes into MnO:Arthur Sutcliffe (1930) Practical Chemistry for Advanced Students (1949 Ed.), John Murray - London. : MnC₂O₄·2H₂O → MnO + CO₂ + CO + 2 H₂O

Applications

Together with manganese sulfate, MnO is a component of

s and food additives. Many thousands of tons are consumed annually for this purpose. Other uses include: a

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

in the manufacture of

allyl alcohol Allyl alcohol ( IUPAC name: prop-2-en-1-ol) is an organic compound with the structural formula . Like many alcohols, it is a water-soluble, colourless liquid. It is more toxic than typical small alcohols. Allyl alcohol is used as a raw material ...

, ceramics, paints, colored glass, bleaching tallow and textile printing.

References

{{oxides Manganese(II) compounds Transition metal oxides Rock salt crystal structure