MANGANESE (II) OXIDE

Production

Manganese(II) oxide is obtained commercially from manganese(IV) oxide (manganese dioxide) by the reduction with hydrogen, carbon monoxide or methane at elevated temperatures (>800°C): MnO2 + CO → MnO + CO2 MnO2 + H2 → MnO + H2O The oxide also can be made by thermal decomposition of manganese(II) carbonate or manganese(II) oxalate in the absence of air: MnCO3 → MnO + CO2 Also, careful dehydration of manganese(II) hydroxide, Mn(OH)2, under controlled conditions in the absence of air yields MnO.

Reactions

Manganese(II) oxide is the lowest oxide of manganese and it is purely a basic oxide. It reacts with acids to form their manganese(II) salts: MnO + H2SO4 → MnSO4 + H2O MnO + 2HCl → MnCl2 + H2O The compound also is oxidized by air or oxygen to higher oxides of manganese. When heated cautiously in air, the product is manganese sesquioxide or manganese(III) oxide: 4MnO + O2 → 2Mn2O3

Flammability and Explosibility

Notclassified

Safety Profile

Moderately toxic by intratracheal and subcutaneous routes. Violent reaction with hydrogen peroxide, Ca(OCl)2, F2, H202. See also MANGANESE COMPOUNDS.

Physical Properties

Green cubic crystal; refractive index 2.16; density 5.37 g/cm3 at 23°C; Moh’s hardness 5.5; melts at 1945°C; insoluble in water.

Occurrence and Uses

Manganese(II) oxide is used in the fertilizer industry as a source of manganese in fertilizers; in feedstuff formulations; and as an intermediate in the production of several manganese compounds.