3D model (
CompTox Dashboard (EPA)
|Molar mass||221.87 g/mol|
|Appearance||dark red oil (room temp.), green if in contact with sulfuric acid|
|Melting point||5.9 °C (42.6 °F; 279.0 K)|
|Boiling point||explodes on heating|
|decomposes to permanganic acid, HMnO4|
|Occupational safety and health (OHS/OSH):|
|explosive, strong oxidizer, very corrosive|
|H201, H271, H314, H330|
|P260, P284, P283, P221|
|NFPA 704 (fire diamond)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Manganese(VII) oxide (manganese heptoxide) is an
Its solubility properties indicate a
Synthesis and reactions
Mn2O7 arises as a dark green oil by the addition of concentrated
- 2 KMnO4 + 2 H2SO4 → Mn2O7 + H2O + 2 KHSO4
Mn2O7 can react further with sulfuric acid to give the remarkable manganyl(VII) cation MnO+
3, which is isoelectronic with CrO3
- Mn2O7 + 2 H2SO4 → 2 [MnO
Mn2O7 decomposes near room temperature, explosively so above 55 °C. The explosion can be initiated by striking the sample or by its exposure to oxidizable organic compounds. The products are MnO2 and O2. Ozone is also produced, giving a strong smell to the substance. The ozone can spontaneously ignite a piece of paper impregnated with an alcohol solution.
Manganese heptoxide reacts with hydrogen peroxide in presence of sulfuric acid, liberating oxygen and ozone:
- ^ Aschoff, H. Ann. Phys. Chem. Ser. 2 volume 111 (1860) page 217 and page 224.
- ^ a b H. Lux (1963). "Manganese(VII) Oxide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY,NY: Academic Press. pp. 1459–1460.
- ^ Wells A.F. (1962) Structural Inorganic Chemistry 3d edition Oxford University Press
- ISBN 0-12-352651-5.