Explosive
Definition and meaning of Explosive in chemistry.
An explosive is a chemical substance or mixture that, once initiated, undergoes extremely rapid, self-sustaining decomposition or reaction, releasing a large volume of hot gas and energy almost instantaneously to produce a powerful shock wave or rapid expansion.
In more detail
Most explosives combine fuel and oxidizing groups (such as nitro, nitrate, or azide) within the same molecule or an intimate mixture, so the reaction does not depend on slow diffusion of external oxygen and can proceed far faster than ordinary combustion. Explosives fall into two broad classes: low explosives, which deflagrate (burn subsonically and are used as propellants), and high explosives, which detonate, meaning the reaction front travels through the material faster than the speed of sound, generating a destructive pressure wave. Sensitivity to heat, friction, or impact depends on the stability of the molecule's bonds, particularly strained or high-nitrogen groups that store large amounts of chemical potential energy.
Key facts
| Types | Low explosives (deflagrate) vs. high explosives (detonate) |
|---|---|
| Detonation velocity | ~1,500–9,000 m/s for common high explosives |
| Example compound | TNT, C7H5N3O6 |
| Field | General Chemistry |
TNT (2,4,6-trinitrotoluene) detonates to form gaseous carbon monoxide, nitrogen, water vapor, and solid carbon, releasing roughly 4.6 megajoules of energy per kilogram almost instantaneously.
Frequently asked questions
What is the difference between deflagration and detonation?
Deflagration is subsonic combustion that propagates by heat conduction, as in burning gunpowder; detonation is a supersonic shock wave that self-propagates through the explosive material, as seen with TNT or dynamite.
Why do explosives release energy so much faster than ordinary fuels?
Because the oxidizer is built into the molecule or premixed at the molecular level, the reaction is not limited by diffusion of atmospheric oxygen, so it can proceed thousands of times faster than typical combustion.