Explosive

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. The material may either be composed solely of one ingredient or be a mixture containing at least two substances. An explosive can be used together with mechanical or electronic components to manufacture a bomb.

The potential energy can be stored in an explosive material in various ways. Most commonly it is stored as chemical energy, such as black powder, nitroglycerin or even grain dust. It can also be stored as pressurized gas, like a gas cylinder, aerosol can, or boiling liquid expanding vapor explosion, or less commonly as nuclear energy, such as in the fissile isotopes uranium-235 and plutonium-239.

Explosive materials may be categorized by the speed at which they expand. Materials that detonate, in which the front of the chemical reaction moves through the material faster than the speed of sound, are called “high explosives.” In contrast, materials that deflagrate, where the front of the reaction moves slower than the speed of sound, are known as “low explosives.” Generally, outcome of the reaction is a rapid burn rather than a proper explosion as seen with high explosives. Explosives may also be categorized by their sensitivity.