Manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

(II) oxide is the inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with formula MnO. MnO is a basic oxide that is insoluble in water but dissolves in acids, forming manganese(II) salts.

Preparation and occurrence

MnO can be prepared by the reduction of any higher oxide with hydrogen e.g.:

MnO₂ + H₂ → MnO + H₂O

Commercially it is prepared by reduction of MnO₂ with hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, carbon monoxide

Carbon monoxide

Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 or methane

Methane

Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

:

MnO₂ + CO → MnO + CO₂

MnO can also be prepared by heating MnCO₃:

MnCO₃ → MnO + CO₂

This calcining process is conducted anaerobically to prevent formation of Mn₂O₃

Manganese(III) oxide

Manganese oxide is the chemical compound of formula Mn2O3.-Preparation and chemistry:Heating MnO2 in air at below 800°C α-Mn2O3 is produced . γ-Mn2O3 can be produced by oxidation followed by dehydration of manganese hydroxide...

.
MnO occurs in nature as the rare mineral manganosite

Manganosite

Manganosite is a rare mineral composed of manganese 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 Furnace, New Jersey. It also occurs in Japan, Kyrgyzstan and...

.

Structure and properties

MnO has the NaCl, rock salt structure, where cations and anions are both octahedrally coordinated. The composition of MnO can vary from MnO to MnO_1.045.
Below 118 K MnO is antiferromagnetic

Antiferromagnetism

In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usuallyrelated to the spins of electrons, align in a regular pattern with neighboring spins pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism...

. MnO has the distinction of being one of the first compounds to have its magnetic structure determined by neutron diffraction in 1951.. This study showed that the Mn²⁺ ions form a face centered cubic magnetic sub-lattice where there are ferromagnetically coupled sheets which are anti-parallel with adjacent sheets.

Applications

Together with manganese sulfate, MnO is a component of fertilizer and feed additives. Many thousands of tons are consumed annually for this purpose.