Mercury(II) fulminate, or Hg(CNO)
2, is a
primary explosive
An explosive (or explosive material) 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 exp ...
. It is highly sensitive to
friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...
, heat and
shock and is mainly used as a trigger for other explosives in
percussion cap
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 ...
s and
detonators. Mercury(II) cyanate, though its chemical formula is identical, has a different atomic arrangement, making the
cyanate and
fulminate anionic isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...
s.
First used as a
priming composition in small copper caps beginning in the 1820s, mercury fulminate quickly replaced
flint
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start ...
s as a means to ignite
black powder
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...
charges in
muzzle-loading
A muzzleloader is any firearm in which the user loads the projectile and the propellant charge into the muzzle end of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern designs of breech-loading fire ...
firearm
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions).
The first firearms originate ...
s. 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.
[ 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(II) azide is an inorganic compound. More so than other azides, it is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder.
Preparation and handling
Lead(II) azi ...
, 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
Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...
and adding ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
to the solution. Edward Charles Howard is credited with first preparing it in 1800.17th century
The 17th century lasted from January 1, 1601 (represented by the Roman numerals MDCI), to December 31, 1700 (MDCC).
It falls into the early modern period of Europe and in that continent (whose impact on the world was increasing) was characterized ...
. The crystal structure
In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat ...
of this compound was determined only in 2007.
Silver fulminate
Silver fulminate (AgCNO) is the highly explosive silver salt of fulminic acid.
Silver fulminate is a primary explosive, but has limited use as such due to its extreme sensitivity to impact, heat, pressure, and electricity. The compound becomes p ...
can be prepared in a similar way, but this salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
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.
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.carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
gas, nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
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
In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...
)
:2 Hg(CNO)2 → 2 CO2 + N2 + Hg + Hg(CN)2 (mercury(II) cyanide
Mercury(II) cyanide, also known as mercuric cyanide, is a poisonous compound of mercury and cyanide. It is an odorless, toxic white powder. It is highly soluble in polar solvents such as water, alcohol, and ammonia, slightly soluble in ether ...
)
See also
* Fulminic acid
* Potassium fulminate
References
External links
National Pollutant Inventory - Mercury and compounds Fact Sheet
*
{{Mercury compounds
Mercury(II) compounds
Fulminates
Explosive chemicals