Funkyyyyyy YouTube. The process for examining evidence at the site of an explosion is very similar to the process followed at the scene of a fire. Ion Mobility Spectrometer. An Ion-mobility spectrometer IMS is an instrument that detects and separates ions in the gas phase. The technique passes absorbed gases through a tube using a carrier gas to promote flow.
The walls of the tube are electrified so that ions with greater charge are more attracted and move slower through the tube. Large ions also move more slowly through the tube. A detector at the end of the tube recognizes the ions based on their charge and shape.
The technique is heavily used by both military and law enforcement purposes; not only detecting explosives but also having use for identification of drugs. Stephanie R. The Chemistry of Explosions. The production of these very low energy stable bonds means that a great deal of energy is released. It should be noted that most explosives contain these same elements.
TNT itself is high energy and unstable. Because these groups are fairly large and in close proximity to each other they cause strain on the structure of the Toluene. Remember that groups of electrons repulse each other.
Other compounds under similar conformational strain are also explosive for this same reason. Primary High Explosives Among the high explosives, primary explosives are those that ultrasensitive to heat, shock, or friction and provide the major ingredients found in blasting caps or primers used to detonate other explosives. Secondary High Explosives Secondary high explosives are those chemicals that do not have to be contained to explode and are relatively stable and safe to handle.
Funkyyyyyy YouTube Collecting Evidence at the Scene of an Explosion The process for examining evidence at the site of an explosion is very similar to the process followed at the scene of a fire.
Search systematically the entire scene and try to locate the epicenter origin of the explosion. Objects located at or near the origin of the explosion must be collected for laboratory examination.
Each object should be placed individually into a sealed airtight metal canister. Some explosive residues are known to be able to seep through plastic containment and contaminate other evidence. Often a crater is located at the origin and loose soil and other debris must be preserved from its interior for laboratory analysis. The second fact that makes TNT explosive is that it is chemically unstable - the nitro groups are so closely packed that they experience a great deal of strain and hindrance to movement from their neighbouring groups.
Thus it doesn't take much of an initiating force to break some of the strained bonds, and the molecule then flies apart. Typically 1 gram of TNT produces about 1 litre of gas, which is a fold increase in volume. This expanding hot gas can be used to propel a projectile, such as a bullet from a gun, or for demolition purposes. There are a number of advantages that TNT has for ammunition manufacturers. Secondly, it is not too unstable - allowing it to be handled reasonably safely during manufacture and operation.
TNT will not spontaneously explode, and in fact can be treated quite roughly. In order to initiate the explosion, TNT must first be detonated using a pressure wave from another, more easily induced explosion from another explosive called a detonator.
One such detonator is lead azide , Pb N 3 2 , which explodes when struck or if an electric discharge is passed through it. Plastic explosives have been around for a couple of decades.
They typically consist of an explosive mixed with an oil or wax plastic resin. One example is C4 plasticized RDX , which has been used by the military and safecrackers! RDX is cyclotrimethylenetrinitramine , another high explosive with a tight, constricted ring structure similar to TNT except containing even more energy-providing N atoms.
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