Mercury(I) oxide

Mercury(I) oxide, also known as mercurous oxide, is an inorganic metal oxide with the chemical formula Hg₂O.

Mercury(I) oxide

Identifiers
CAS Number	15829-53-5 Y[1]
3D model (JSmol)	Interactive image Interactive image
ChemSpider	17615579 Y
ECHA InfoCard	100.036.289
EC Number	239-934-0
PubChem CID	16683011
UNII	0I308SWC92 Y
UN number	1641
CompTox Dashboard (EPA)	DTXSID3065954
InChI InChI=1S/2Hg.O Y Key: RPZHFKHTXCZXQV-UHFFFAOYSA-N Y[1]
SMILES O([Hg])[Hg] [O-2].[Hg+].[Hg+]
Properties
Chemical formula	Hg2O
Molar mass	417.183 g·mol−1
Appearance	Very dark, orange, opaque crystals
Odor	Odourless
Density	9.8 g mL−1
Magnetic susceptibility (χ)	−76.3·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	highly toxic
GHS labelling:[2]
Pictograms
Signal word	Danger
Hazard statements	H315, H317, H320, H335, H341, H361, H370, H372
Precautionary statements	P201, P202, P260, P261, P264, P270, P271, P272, P280, P281, P302+P352, P304+P340, P305+P351+P338, P307+P311, P308+P313, P312, P314, P321, P332+P313, P333+P313, P337+P313, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 0 1
Lethal dose or concentration (LD, LC):
LD50 (median dose)	18 mg/kg (oral, rat)[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

It is a brown/black powder, insoluble in water but soluble in nitric acid. With hydrochloric acid, it reacts to form calomel, Hg₂Cl₂.^[4] Mercury(I) oxide is toxic but without taste or smell. It is chemically unstable and converts to mercury(II) oxide and mercury metal.