Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: taregg on 05/11/2012 00:54:26

Title: three types of reaction materials explostion question
Post by: taregg on 05/11/2012 00:54:26
Materials that are readily to explosive when if it,s decomposition, polymerizatigon, or self-reaction at normal temperature .......what do is it mean with an example.
Title: Re: three types of reaction materials explostion question
Post by: taregg on 08/11/2012 13:43:25
can some body please answer my questlon.....
Title: Re: three types of reaction materials explostion question
Post by: yor_on on 08/11/2012 15:33:48
Decomposition is a slow 'burn'
Sorry, that one can also be fast, it was me thinking wrong (garden wise sort of:). There is apparently something called 'Explosive decomposition' which also can 'self react'.

"It is the speed of the decomposition reaction which makes nitroglycerin such a violent explosive. Unlike burning, which can only travel as fast as the flame front can move through the material, high explosives are decomposed almost instantaneously by a supersonic shock wave passing through the material. This instantaneous destruction of all the molecules in the sample is called a detonation, and the rapid expansion of hot gases that results is what causes the destructive blast. In fact, 4 moles of nitroglycerin produces 35 moles of hot gases."

polymerization can be slow, or fast, also involving self reactions.

"Polymers are very large molecules made up of smaller parts called monomers. The process of joining the smaller parts to form the very large molecule is called polymerization. Another chemical, called a cross-linking agent is required to bring the parts together to form the very large molecules. In the case of synthetic (man-made) polymers, the cross-linking agent could be a peroxide or maybe a metal ion or other chemical. Nature uses enzymes in the cross-linking process. A lot of heat can be released in the manufacture of synthetic polymers. The reaction also can occur quickly, even in a second. The quick heat release can vaporize the monomer or other flammables resulting in an explosive vapor cloud. The buildup of flammable gases can “explode” the reaction vessel or container, or if the vapors are released by a “safety valve”, a spark can ignite the vapors creating a vapor cloud explosion."

self reactions can be slow or fast depending on what is involved, a atomic bomb is a self-sustaining nuclear chain reaction.

And then there is oxidation?

"Burning is an example of rapid oxidation; rusting is an example of slow oxidation."

"autooxidation or auto-oxidation. A slow, easily initiated, self-catalyzed reaction, generally by a free radical mechanism, between a substance and atmospheric oxygen. Initiators of autoxidation include heat, light, catalysts such as metals, and free radical generators. Davies (1961) defines autoxidation as interaction of a substance with molecular oxygen below 120°C without flame. Possible consequences of autoxidation include
pressure buildup by gas evolution, autoignition by heat generation with inadequate heat dissipation, and the formation of peroxides"

As far as I understand it's all about what energy that will be released over a specified amount of time

Phieww :)
Title: Re: three types of reaction materials explostion question
Post by: Soul Surfer on 15/11/2012 10:06:33
The basic principle of any explosive material is that the material or mixture of materials has a violent chemical or physical reaction that results in a sudden very large increase in volume this is generally the conversion of a solid to a gas by an energetic chemical reaction of any kind  but it could also be an inert gas held at extreme pressure in a container that is ruptured suddenly into small pieces. 

It is also possible to create small explosions by having a solid under extreme stress by its surface that just fragments when a crack is initiated.  See "Rupert's drops"