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 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
| |
| |
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 | |
Occupational safety and health (OHS/OSH): | |
Main hazards | Highly toxic, shock sensitive explosive |
NFPA 704 (fire diamond) | |
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). |
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.
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]
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.
An explosive is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances.
Carbon compounds are defined as chemical substances containing carbon. More compounds of carbon exist than any other chemical element except for hydrogen. Organic carbon compounds are far more numerous than inorganic carbon compounds. In general bonds of carbon with other elements are covalent bonds. Carbon is tetravalent but carbon free radicals and carbenes occur as short-lived intermediates. Ions of carbon are carbocations and carbanions are also short-lived. An important carbon property is catenation as the ability to form long carbon chains and rings.
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.
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.
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.
In chemistry, azide is a linear, polyatomic anion with the formula N−3 and structure −N=N+=N−. It is the conjugate base of hydrazoic acid HN3. Organic azides are organic compounds with the formula RN3, containing the azide functional group. The dominant application of azides is as a propellant in air bags.
A centre-fire is a type of metallic cartridge used in firearms, where the primer is located at the center of the base of its casing. Unlike rimfire cartridges, the centerfire primer is typically a separate component seated into a recessed cavity in the case head and is replaceable by reloading the cartridge.
Silver fulminate (AgCNO) is the highly explosive silver salt of fulminic acid.
Pseudohalogens are polyatomic analogues of halogens, whose chemistry, resembling that of the true halogens, allows them to substitute for halogens in several classes of chemical compounds. Pseudohalogens occur in pseudohalogen molecules, inorganic molecules of the general forms Ps–Ps or Ps–X, such as cyanogen; pseudohalide anions, such as cyanide ion; inorganic acids, such as hydrogen cyanide; as ligands in coordination complexes, such as ferricyanide; and as functional groups in organic molecules, such as the nitrile group. Well-known pseudohalogen functional groups include cyanide, cyanate, thiocyanate, and azide.
Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity into two or more fragments. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction.
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.
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%).
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.
The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.
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 covalent bond between mercury and carbon.
Tetrazene is an explosive material used for sensitization of priming compositions. It is a derivative of the compound with the IUPAC name tetrazene.
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.
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