What makes nitroglycerin so dangerous?
which the two atoms are held together by an extremely strong triple covalent bond. In addition, the oxygen also reacts with the carbon and hydrogen present to form water and carbon dioxide. The enthalpies of formation of these products are far lower than that of the original molecule, and subsequently the decomposition of an explosive is an exothermic process which releases a great deal of energy. This energy excites the surrounding air and the gases produced through decomposition to form a destructive blast wave, which is the cause of the majority of the damage done by explosives. 4 Although the compounds formed by oxygen as a result of decomposition are not responsible for as great a release in energy as the N 2 formed, they do, however, play a particularly important role. This is primarily because, owing to having such a negative enthalpy of formation, all nitrogen released reacts to formN 2 , leaving only oxygen to react with the carbon and hydrogen. Therefore, enough oxygenmust be present in the molecule to oxidize the carbon and hydrogen, and ensure that the energy released in the explosion is maximized. Nearly every commonly used high explosive contains oxygen for this reason. However, many do not contain enough to fully oxidize all of the products of decomposition. The ability of the oxygen atoms contained within amolecule to fully oxidize all these products is known as a compound’s ‘ oxygen balance, ’ and is given in the form of a percentage. An explosive’s oxygen balance plays a large r ole in determining the power of the shockwave it produces, and hence its destructiveness. Many common explosives have negative oxygen balances, which means there is insufficient oxygen contained within the molecule to fully oxidize the products of decomposition, and hence the energy released through decomposition is limited. Conversely, those compounds with oxygen balances around or above 0 tend to be more powerful upon detonation. 5 To understand nitroglycerin’s oxygen balance in relation to those of other explosives, we will introduce two commonly used explosives with which to compare it to: firstly trinitrotoluene ( ‘ TNT ’ ), an explosive widely used in both military and civil applications, which is also used as the standard measure against which the destructive power of all other explosives are measured (known as the relative effectiveness factor, or ‘ RFE, ’ where the RFE of TNT is 1.00):
Skeletal formula of TNT
Image Source: Sigma-Aldrich 2,4,6 – Trinitrotoluene solution
4 See Federation of American Scientists, Chemical Explosives. 5 See Federation of American Scientists, Chemical Explosives.
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