Substances releasing large gas volumes rapidly, such as TNT and nitroglycerin.
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Explosives release large volumes of gas and heat very rapidly, because the molecules or mixtures contain both fuel and oxidiser and react in a fast, self-sustaining reaction. Detonation is a supersonic reaction front that travels through the material at kilometres per second, while deflagration is subsonic burning. Nitroglycerin, TNT, RDX and PETN are high explosives, whereas black powder and ammonium nitrate mixed with fuel oil are lower-energy mixtures. Alfred Nobel made nitroglycerin safer to handle by absorbing it into an inert earth, producing dynamite in 1867. Safe handling depends on sensitivity, stability and storage conditions.
Key ideas: An explosion is a fast exothermic reaction that makes large volumes of hot gas. Types: low explosives deflagrate (black powder KNO3 plus charcoal plus sulfur), high explosives detonate (TNT, nitroglycerin, RDX, PETN) with supersonic shock waves at 6000 to 9000 m per s. Nitro groups provide oxygen inside the molecule. Nobel stabilized nitroglycerin on kieselguhr as dynamite.
Common mistakes and connections: Mistake: thinking explosives need external oxygen; many contain their own oxidizer. Detonation differs from burning in speed and shock. Oxygen balance predicts completeness of combustion. Ammonium nitrate decomposes to N2, O2 and water, giving gases. Links to enthalpy, kinetics and nitrogen chemistry.
Approximate energy released per kilogram. Explosives are powerful mainly because they release gas and heat extremely fast, not because of large energy per mass. The interactive lesson shows this as a live animation or chart.
Detonating TNT releases roughly 4.2 MJ of energy per kilogram.
Substances releasing large gas volumes rapidly, such as TNT and nitroglycerin.
Explosives is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Biochemistry, Environment & Industry first: Glass Manufacture, Cement Manufacture, Fertilizer Production.
The next topics in Biochemistry, Environment & Industry are Fireworks Chemistry and Matches.
Yes. The interactive lesson includes a self-check question on Explosives, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Explosives is topic 107 of 127 in Biochemistry, Environment & Industry.
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