Question: What is the most explosive chemical?

Mark Hill answered on 24 Mar 2011:

Hello student 10,

This isn’t really my field of expertise. I can remember finding a few when I did chemistry A level – by accident!

It depends on whether you mean the most explosively unstable compound, or the one with the greatest explosive energy for quantity.

Explosives also differ according to the type of explosion that is wanted. For example, an incendiary device would usually produce a lower power of explosion, but would have a composition that commenced an exothermic reaction to set a fire.

An explosive designed for quarrying would be of a different compound, quite stable in transportation and storage, but capable of a rapid and high energy explosion, to blast rock. It has to be relatively stable, to allow for sequential, multi-site blasting. Quarrying and tunnelling blasts generally have several charges, which fire in a set order,very quickly after one another, to ensure that the rock blasts in a controlled manner. Semtex is a classic trade name compound for quarrying.

Weapons grade explosives are also very different, according to what is to be blown up. Explosive in the percussion cap of a live round has to be both relatively stable, but to ignite and explode very quickly, in order to accelerate the shell, or bullet down the gun chamber.

A very common explosive material is probably kept in your family car; in fact there are probably up to a dozen of them. They are the azide based explosive charges inside airbags and seat belt pre-tensioners (system for pulling the seat-belt tight on you just before a crash. It works by the explosive being electronically triggered, inside a small capsule, under the seat, which pulls a cable tight, pulling the belt tight. Nasty stuff, but in a small well contained structure.

Other types of explosive range from black powder ( a really old sulphur and carbon mixture, with a few other things) to amatol based liquids, which are not very stable, and PBX, or plastic explosives. This is just the start of a very big subject. I hope that I have helped.

Mark.