Potassium manganate

Names
IUPAC name Potassium manganate(VI)
Identifiers
CAS Number	10294-64-1 Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.030.592
EC Number	233-665-2
PubChem CID	160931
CompTox Dashboard (EPA)	DTXSID10893107
SMILES [O-][Mn](=O)(=O)[O-].[K+].[K+
Properties
Chemical 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	0 1 1 OX
R-phrases	8-36/37/38
S-phrases	17-26-36/37/39
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

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

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".

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.

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

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

• Permanganate
• Manganese(VII) oxide