Mercury(II) fulminate

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Mercury(II) fulminate
Mercury-fulminate-3D-vdW.png
Mercury-fulminate-xtal-3D-vdW.png
Mercuryfulminate puryfied.jpg
Names
IUPAC name
Mercury(II) fulminate
Systematic IUPAC name
Dioxycyanomercury
Other names
Fulminated Mercury
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.053 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/2CNO.Hg/c2*1-2-3; Yes check.svgY
    Key: MHWLNQBTOIYJJP-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/2CNO.Hg/c2*1-2-3;/rC2HgN2O2/c6-4-1-3-2-5-7
    Key: MHWLNQBTOIYJJP-HZIBCBEIAJ
  • [O-][N+]#C[Hg]C#[N+][O-]
Properties
C2N2O2Hg
Molar mass 284.624 g/mol
AppearanceGrey, 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
Occupational safety and health (OHS/OSH):
Main hazards
Highly toxic, shock sensitive explosive
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerinSpecial hazards (white): no code
4
1
4
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).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

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 anions isomers.

Contents

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)

See also

Related Research Articles

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<span class="mw-page-title-main">Nitrogen</span> Chemical element with atomic number 7 (N)

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colourless and odourless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.

<span class="mw-page-title-main">Detonator</span> Small explosive device used to trigger a larger explosion

A detonator is a device used to make an explosive or explosive device explode. Detonators come in a variety of types, depending on how they are initiated and details of their inner working, which often involve several stages. Types of detonators include non-electric and electric. Non-electric detonators are typically stab or pyrotechnic while electric are typically "hot wire", exploding bridge wire or explosive foil.

<span class="mw-page-title-main">Percussion cap</span> Ignition source in a type of firearm mechanism

The percussion cap, percussion primer, or caplock, introduced in the early 1820s, is a type of single-use percussion ignition device for muzzle loader firearm locks enabling them to fire reliably in any weather condition. Its invention gave rise to the caplock mechanism or percussion lock system which used percussion caps struck by the hammer to set off the gunpowder charge in rifles and cap and ball firearms. Any firearm using a caplock mechanism is a percussion gun. Any long gun with a cap-lock mechanism and rifled barrel is a percussion rifle. Cap and ball describes cap-lock firearms discharging a single bore-diameter spherical bullet with each shot.

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<span class="mw-page-title-main">Silver fulminate</span> High explosive used in bang snaps

Silver fulminate (AgCNO) is the highly explosive silver salt of fulminic acid.

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<span class="mw-page-title-main">Fulminate</span> Chemical compounds containing an –O–N≡C group

Fulminates are chemical compounds which include the fulminate ion. The fulminate ion is a pseudohalic ion because its charge and reactivity are similar to those of the halogens. Due to the instability of the ion, fulminate salts are friction-sensitive explosives. The best known is mercury(II) fulminate, which has been used as a primary explosive in detonators. Fulminates can be formed from metals, such as silver and mercury, dissolved in nitric acid and reacted with ethanol. The weak single nitrogen-oxygen bond is responsible for their instability. Nitrogen very easily forms a stable triple bond to another nitrogen atom, forming nitrogen gas.

<span class="mw-page-title-main">Cyanate</span> Anion with formula OCN and charge –1

The cyanate ion is an anion with the chemical formula OCN. It is a resonance of three forms: [O−C≡N] (61%) ↔ [O=C=N] (30%) ↔ [O+≡C−N2−] (4%).

<span class="mw-page-title-main">Mercury(II) thiocyanate</span> Chemical compound

Mercury(II) thiocyanate is an inorganic chemical compound, the coordination complex of Hg2+ and the thiocyanate anion. It is a white powder. It will produce a large, winding "snake" when ignited, an effect known as the Pharaoh's serpent.

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<span class="mw-page-title-main">Potassium fulminate</span> Chemical compound

Potassium fulminate is the potassium salt of the fulminate ion. Its only use, aside from chemical demonstrations, is in the percussion caps for some early rifles. Usually prepared by reacting a potassium amalgam with mercury fulminate, it is much less sensitive due to the ionic bond between potassium and carbon, unlike the weaker covalent bond between mercury and carbon.

<span class="mw-page-title-main">Potassium ferrioxalate</span> Chemical compound

Potassium ferrioxalate, also called potassium trisoxalatoferrate or potassium tris(oxalato)ferrate(III) is a chemical compound with the formula K3[Fe(C2O4)3]. It often occurs as the trihydrate K3[Fe(C2O4)3]·3H2O. Both are crystalline compounds, lime green in colour.

<span class="mw-page-title-main">Tetrazene explosive</span> Chemical compound

Tetrazene is an explosive material used for sensitization of priming compositions. It is a derivative of the compound with the IUPAC name tetrazene.

<span class="mw-page-title-main">Silver nitride</span> Chemical compound

Silver nitride is an explosive chemical compound with symbol Ag3N. It is a black, metallic-looking solid which is formed when silver oxide or silver nitrate is dissolved in concentrated solutions of ammonia, causing formation of the diammine silver complex which subsequently breaks down to Ag3N. The standard free energy of the compound is about +315 kJ/mol, making it an endothermic compound which decomposes explosively to metallic silver and nitrogen gas.

Sodium cyanate is the inorganic compound with the formula NaOCN. A white solid, it is the sodium salt of the cyanate anion.

<span class="mw-page-title-main">Nickel hydrazine nitrate</span> Chemical compound

Nickel hydrazine nitrate (NHN), (chemical formula: [Ni(N2H4)3](NO3)2 is an energetic material having explosive properties in between that of primary explosive and a secondary explosive. It is a salt of a coordination compound of nickel with a reaction equation of 3N2H4·H2O + Ni(NO3)2 →〔Ni(N2H4)3〕(NO3)2 + 3H2O

References

  1. 1 2 Wisniak, Jaime (2012). "Edward Charles Howard. Explosives, meteorites, and sugar". Educación Química. 23 (2). Universidad Nacional Autonoma de Mexico: 230–239. doi: 10.1016/s0187-893x(17)30114-3 . ISSN   0187-893X.
  2. 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. S2CID   138658702.
  3. W. Beck; J. Evers; M. Göbel; G. Oehlinger; 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 .
  4. "The Sciences - Fulminating Substances". Scientific American. 11 June 1853.
  5. W. E. Garner & H. R. Hailes (1933). "Thermal decomposition and detonation of mercury fulminate". Proceedings of the Royal Society of London. 139 (1–3): 1–40. Bibcode:1933CP....334..128S. doi: 10.1098/rspa.1933.0040 .