Potassium manganate

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Potassium manganate
Potassium-manganate-unit-cell-3D-balls.png
IUPAC name Potassium manganate(VI)
Identifiers
CAS number 10294-64-1
PubChem 160931
EC number 233-665-2
SMILES [O-][Mn](=O)(=O)[O-].[K+].[K+
Properties
Molecular formula K2MnO4
Molar mass 197.132 g/mol
Appearance dark green crystals
Density 2.78 g/cm3, solid
Melting point

190 °C

Solubility in water decomposes
Acidity (pKa) 7.1
Structure
Crystal structure isomorphous with K2SO4
Coordination
geometry
tetrahedral anion
Hazards
Main hazards oxidizer
NFPA 704

NFPA 704.svg

0
1
1
OX
R-phrases 8-36/37/38
S-phrases 17-26-36/37/39
Related compounds
Related compounds KMnO4
MnO2
K2CrO4
K2FeO4
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Potassium manganate is a chemical compound. Its chemical formula is K2MnO4. It contains potassium and manganate ions.

Properties[change | edit source]

Potassium manganate is a green solid. It can disproportionate into potassium permanganate and manganese(IV) oxide. This happens in acidic pH. This reaction, because of its color change, is known as a "chemical chameleon".

Preparation[change | edit source]

It is made by reacting manganese(IV) oxide with very hot potassium hydroxide. Sometimes oxygen or potassium nitrate is used as the oxidizing agent. This makes potassium manganate. Normally the potassium manganate is converted to potassium permanganate. Potassium permanganate is more common. Potassium iodide can reduce potassium permanganate to potassium manganate. It can also be made by reacting hot potassium permanganate with potassium hydroxide. This makes oxygen and potassium manganate.

Uses[change | edit source]

Potassium manganate does not have many uses. It is mainly made when potassium permanganate is made.

Safety[change | edit source]

Potassium manganate is a moderate oxidizing agent. When it is reduced, it can made black or brown stains on glass, clothing, or skin.

Related pages[change | edit source]