Explosive

The remainder are too dangerous, sensitive, toxic, expensive, unstable, or prone to decomposition or degradation over short time spans.

Certain materials—dusts, powders, gases, or volatile organic liquids—may be simply combustible or flammable under ordinary conditions, but become explosive in specific situations or forms, such as dispersed airborne clouds, or confinement or sudden release.

[11] An explosion is a type of spontaneous chemical reaction that, once initiated, is driven by both a large exothermic change (great release of heat) and a large positive entropy change (great quantities of gases are released) in going from reactants to products, thereby constituting a thermodynamically favorable process in addition to one that propagates very rapidly.

Consequently, most commercial explosives are organic compounds containing –NO2, –ONO2 and –NHNO2 groups that, when detonated, release gases like the aforementioned (e.g., nitroglycerin, TNT, HMX, PETN, nitrocellulose).

While these definitions are distinct, the problem of precisely measuring rapid decomposition makes practical classification of explosives difficult.

[14] The shock front is capable of passing through the high explosive material at supersonic speeds — typically thousands of metres per second.

Examples include nuclear explosives, and abruptly heating a substance to a plasma state with a high-intensity laser or electric arc.

Some of the more important characteristics are listed below: Sensitivity refers to the ease with which an explosive can be ignited or detonated, i.e., the amount and intensity of shock, friction, or heat that is required.

The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired.

The explosive lenses around nuclear charges are also designed to be highly insensitive, to minimize the risk of accidental detonation.

Reference is made to the Sellier-Bellot scale that consists of a series of 10 detonators, from n. 1 to n. 10, each of which corresponds to an increasing charge weight.

In practice, most of the explosives on the market today are sensitive to an n. 8 detonator, where the charge corresponds to 2 grams of mercury fulminate.

Together with density it is an important element influencing the yield of the energy transmitted for both atmospheric over-pressure and ground acceleration.

[15] In contrast, a "high explosive", whether a primary, such as detonating cord, or a secondary, such as TNT or C-4, has a significantly higher burn rate about 6900–8092 m/s.

Explosive power or performance is evaluated by a tailored series of tests to assess the material for its intended use.

In addition to strength, explosives display a second characteristic, which is their shattering effect or brisance (from the French meaning to "break").

It is possible to compress an explosive beyond a point of sensitivity, known also as dead-pressing, in which the material is no longer capable of being reliably initiated, if at all.

Volatility affects the chemical composition of the explosive such that a marked reduction in stability may occur, which results in an increase in the danger of handling.

Manufacturing inputs can also be organic compounds or hazardous materials that require special handling due to risks (such as carcinogens).

The decomposition products, residual solids, or gases of some explosives can be toxic, whereas others are harmless, such as carbon dioxide and water.

[18] Gaseous volumes computed by the ideal gas law tend to be too large at high pressures characteristic of explosions.

[18] Attempts to obtain more precise volume estimates must consider the possibility of such side reactions, condensation of steam, and aqueous solubility of gases like carbon dioxide.

For example, dynamite is a mixture of highly sensitive nitroglycerin with sawdust, powdered silica, or most commonly diatomaceous earth, which act as stabilizers.

Explosive compounds are also often "alloyed": HMX or RDX powders may be mixed (typically by melt-casting) with TNT to form Octol or Cyclotol.

In other situations, different signals such as electrical or physical shock, or, in the case of laser detonation systems, light, are used to initiate an action, i.e., an explosion.

Under normal conditions, low explosives undergo deflagration at rates that vary from a few centimetres per second to approximately 0.4 kilometres per second (1,300 ft/s).

Countless high-explosive compounds are chemically possible, but commercially and militarily important ones have included NG, TNT, TNP, TNX, RDX, HMX, PETN, TATP, TATB, and HNS.

It is an internationally accepted system that communicates using the minimum amount of markings the primary hazard associated with a substance.

[30] Listed below are the Divisions for Class 1 (Explosives): To see an entire UNO Table, browse Paragraphs 3–8 and 3–9 of NAVSEA OP 5, Vol.

The illegal use of explosives is covered under the Wet Wapens en Munitie (Weapons and Munition Act)[32] (Dutch).