Mercury(II) fulminate

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Mercury(II) fulminate
Mercury fulminate.svg
Mercury-fulminate-3D-vdW.png
Mercury-fulminate-xtal-3D-vdW.png
Mercuryfulminate puryfied.jpg
Names
Other names
Fulminated Mercury
Identifiers
628-86-4 N
ChEBI CHEBI:39152 YesY
ChemSpider 9197626 YesY
Jmol-3D images Image
PubChem 11022444
Properties
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)
slightly soluble
Solubility soluble in ethanol, ammonia
Explosive data
Shock sensitivity High
Friction sensitivity High
Detonation velocity 4250 m/s
Hazards
Main hazards Highly Toxic, Shock Sensitive Explosive
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).
 N verify (what isYesY/N?)
Infobox references

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

First used as a priming composition in small copper caps after the 1830s, 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 or potassium chlorate became widely used in primers for self-contained rifle and pistol ammunition. Mercury fulminate has the distinct advantage over potassium chlorate of being non-corrosive, but it is known to weaken with time. 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 require mercury for manufacture, supplies of which can be unreliable in wartime.[citation needed]

Preparation[edit]

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.[1] The crystal structure of this compound was only determined in 2007.[2]

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

Decomposition[edit]

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.[3]

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)

See also[edit]


References[edit]

  1. ^ Edward Howard (1800). "On a New Fulminating Mercury". Philosophical Transactions of the Royal Society of London 90 (1): 204–238. doi:10.1098/rstl.1800.0012. 
  2. ^ W. Beck, J. Evers, M. Göbel, G. Oehlinger and T. M. Klapötke (2007). "The Crystal and Molecular Structure of Mercury Fulminate (Knallquecksilber)". Zeitschrift für anorganische und allgemeine Chemie 633 (9): 1417–1422. doi:10.1002/zaac.200700176. 
  3. ^ W. E. Garner & H. R. Hailes (1933). "Thermal decomposition and detonation of mercury fulminate" (PDF). Proceedings of the Royal Society of London 139 (1–3): 1–40. Bibcode:1933CP....334..128S. doi:10.1098/rspa.1933.0040. Retrieved 2013-03-11. 
Mercury fulminate

External links[edit]