Explosives in History Adapted from Napoleon’s Buttons by Penny Le Couteur and Jay Burreson, Chapter 5

Explosive History Gunpowder was the first known explosive, and it was used initially for fireworks and firecrackers. These explosives were used in China, India, and the Middle East, but its ingredients were not recorded until about 1000 A.D. By 1067 A.D., the Chinese government controlled gunpowder production. The first reports of gunpowder in Europe occur in 1250 A.D. Over time, Europeans perfected methods of producing high quality gunpowder by using “urine of wine-drinking bishops” during the production process.

What’s the Chemistry? Gunpowder is a physical mixture of saltpeter (potassium nitrate), charcoal, and sugar. 4KNO3(s) + 7C(s) + S(s)  3CO2(g) + 3CO(g) + 2N2(g) + K2CO3(s) + K2S(s) Wow so many moles of gas on the right, much explosions! That white smoke in the air after a gunpowder explosion? K2CO3 and K2S.

Chemistry of Explosions All explosives have three features: Explosions are exothermic! Explosions produce large volumes of gases! Explosions must occur extremely rapidly! Most explosive reactions produce very stable gas molecules such as N2 If an explosion is not rapid then there wouldn’t be any damaging output. Oxygen often has to come from within the molecule. Both are C7H7NO2! Nitro groups are almost always found in explosives.

Nitrocellulose Friedrich Schönbein is a chemist who discovered ozone in 1840. Although his wife had forbidden him to do so, Schönbein occasionally experimented at home in the kitchen. One day in 1845, when his wife was away, he spilled a mixture of nitric acid and sulfuric acid. After using his wife's cotton apron to mop it up, he hung the apron over the stove to dry, only to find that the cloth spontaneously exploded. Turns out he added a bunch of nitro groups to the cellulose in the apron!

4C3H5N3O9(l)  12CO2(g) + 6N2(g) + 10H2O(g) + O2 (g) Nitroglycerin Ascanio Sobrero first synthesized nitroglycerin in 1847. He mixed HNO3 with glycerin and got an oil. He tasted the oil... “A trace placed on the tongue but not swallowed gives rise to a most pulsating, violent headache, accompanied by great weakness of the limbs.” In later years, it was shown that nitroglycerin releases nitric oxide (NO) in the body, which dilates blood vessels. HNO3 4C3H5N3O9(l)  12CO2(g) + 6N2(g) + 10H2O(g) + O2 (g)

Nobel’s Dynamite Idea Alfred Nobel’s family owned an explosives factory that started to sell nitroglycerin in 1864 in Stockholm, Sweden. An accidental explosion killed his brother, Emil Nobel, but the Nobel company expanded to have factories in 11 countries, even the US. The problem was that nitroglycerin is unpredictable and will explode on shock or heating. Eventually he found that mixing nitroglycerin with diatomaceous earth, a stable putty could be made. Nobel was a pacifist and he believed the destructive power of dynamite would be a deterrent to war.

2C7H5N3O6(l)  7CO (g) + 3N2(g) + 5H2O (g) + 7C (s) TriNitroToluene 2C7H5N3O6(l)  7CO (g) + 3N2(g) + 5H2O (g) + 7C (s) TNT TNT is difficult to detonate and also less powerful than other explosives, which makes it attractive from a safety standpoint. It is often mixed with other explosives, and is still the explosive of choice in modern day.

Other Explosives Pentaerythritoltetranitrate (PETN) can be mixed with rubber to make an explosive of any shape. Favored by terrorists, it is easy to detonate and powerful, and very difficult to detect. Research Department Explosive (RDX) is about 1.5 times more powerful than TNT. Main component is C4 explosives. Nuclear weapons are about 1000 times more powerful than TNT. They are destructive enough to have deterred their use…