An entropic explosion is an explosion

Explosion

An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

 in which the reactants undergo a large change in volume without releasing a large amount of heat. The chemical decomposition

Chemical decomposition

Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...

 of triacetone triperoxide

Acetone peroxide

Acetone peroxide is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor....

 or TATP is an example of an entropic explosion. It is not a thermochemically

Thermochemistry

Thermochemistry is the study of the energy and heat associated with chemical reactions and/or physical transformations. A reaction may release or absorb energy, and a phase change may do the same, such as in melting and boiling. Thermochemistry focuses on these energy changes, particularly on the...

 highly favored event (not much energy generated in chemical bond

Chemical bond

A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 formation in reaction products). It rather involves an entropy

Entropy

Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...

 burst, which is the result of formation of one ozone

Ozone

Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

 and three acetone

Acetone

Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...

 gas phase molecules from every molecule of TATP in the solid state.

External links and references

• Dubnikova, F.; Kosloff, R.; Almog, J.; Zeiri, Y.; Boese, R.; Itzhaky, H.; Alt, A.; Keinan, E.; J. Am. Chem. Soc.; (Article); 2005; 127(4); 1146-1159.
• The Skaggs Institute for Chemical Biology 2004 "The calculated thermal decomposition pathway of the TATP molecule was a complicated multistep process with several highly reactive intermediates, including singlet molecular oxygen and various biradicals. Of note, the calculations predict formation of acetone and ozone as the main decomposition products and not the intuitively expected oxidation products. The key conclusion from this study is that the explosion of TATP is not a thermochemically highly favored event. Rather, the explosion involves entropy burst, which is the result of formation of 4 gas-phase molecules from every molecule of TATP in the solid state. Quite unexpectedly, the 3 isopropylidene units of the TATP molecule do not play the role of fuel that can be oxidized and release energy during the explosion. Instead, these units function as molecular scaffolds that hold the 3 peroxide units close together spatially in the appropriate orientation for the decomposition chain reaction."
• Israeli Invention Detects TATP Explosives "To our great surprise,” PET’s inventor, Prof. Ehud Keinan, Dean of the Technion's Faculty of Chemistry, wrote in the Journal of the American Chemical Society, “we discovered that TATP is very different from all other conventional explosives in that it does not release heat during the explosion. It explodes by rapid decomposition of every solid-state molecule to four gas-phase molecules. This rare phenomenon, scientifically known as 'Entropic Explosion', is reminiscent of the rapid reaction that produces gas in the safety air-bags of cars during accidents."
• Chemical and Engineering News PDF