PROFILPELAJAR.COM

Mercury(II) fulminate
Names
	IUPAC name Mercury(II) fulminate
	Systematic IUPAC name Dioxycyanomercury
	Other names Fulminated Mercury
Identifiers
CAS Number	628-86-4 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:39152 ;
ChemSpider	9197626 ;
ECHA InfoCard	100.010.053
PubChem CID	11022444;
UNII	O8H2ZFF76L ;
CompTox Dashboard (EPA)	DTXSID40893599 ;
	InChI InChI=1S/2CNO.Hg/c21-2-3; Key: MHWLNQBTOIYJJP-UHFFFAOYSA-N ; InChI=1/2CNO.Hg/c21-2-3;/rC2HgN2O2/c6-4-1-3-2-5-7 Key: MHWLNQBTOIYJJP-HZIBCBEIAJ;
	SMILES [O-][N+]#C[Hg]C#[N+][O-];
Properties
Chemical formula	C2N2O2Hg
Molar mass	284.624 g/mol
Appearance	Grey, pale brown, or white crystalline solid
Density	4.42 g/cm3
Melting point	160 °C (320 °F; 433 K)
Boiling point	356.6 °C (673.9 °F; 629.8 K)
Solubility in water	slightly soluble
Solubility	soluble in ethanol, ammonia
Explosive data
Shock sensitivity	High
Friction sensitivity	High
Detonation velocity	4250 m/s
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Highly toxic, shock sensitive explosive
NFPA 704 (fire diamond)	4 1 4
Autoignition; temperature	170 °C (338 °F; 443 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Mercury(II) fulminate, or Hg(CNO)₂, is a primary explosive. It is highly sensitive to friction, heat and shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though its chemical formula is identical, has a different atomic arrangement, making the cyanate and fulminate anionic isomers.

First used as a priming composition in small copper caps beginning in the 1820s, mercury fulminate quickly replaced flints as a means to ignite black powder charges in muzzle-loading firearms. Later, during the late 19th century and most of the 20th century, mercury fulminate became widely used in primers for self-contained rifle and pistol ammunition; it was the only practical detonator for firing projectiles until the early 20th century.^[1] Mercury fulminate has the distinct advantage over potassium chlorate of being non-corrosive, but it is known to weaken with time, by decomposing into its constituent elements. The reduced mercury which results forms amalgams with cartridge brass, weakening it, as well. Today, mercury fulminate has been replaced in primers by more efficient chemical substances. These are non-corrosive, less toxic, and more stable over time; they include lead azide, lead styphnate, and tetrazene derivatives. In addition, none of these compounds requires mercury for manufacture, supplies of which can be unreliable in wartime.

Preparation

Mercury(II) fulminate is prepared by dissolving mercury in nitric acid and adding ethanol to the solution. It was first prepared by Edward Charles Howard in 1800.^[2]^[1] The crystal structure of this compound was determined only in 2007.^[3]

Silver fulminate can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can explode even under water and is impossible to accumulate in large amounts because it detonates under its own weight.^[4]

Decomposition

The thermal decomposition of mercury(II) fulminate can begin at temperatures as low as 100 °C, though it proceeds at a much higher rate with increasing temperature.^[5]

A possible reaction for the decomposition of mercury(II) fulminate yields carbon dioxide gas, nitrogen gas, and a combination of relatively stable mercury salts.

4 Hg(CNO)₂ → 2 CO₂ + N₂ + HgO + 3 Hg(OCN)CN

Hg(CNO)₂ → 2 CO + N₂ + Hg

Hg(CNO)₂ → :Hg(OCN)₂ (cyanate or / and isocyanate)

2 Hg(CNO)₂ → 2 CO₂ + N₂ + Hg + Hg(CN)₂ (mercury(II) cyanide)