Explosives and propellants are typically a combination of an oxidizer and a fuel. The first explosive, gunpowder or black powder, was invented by the Chinese in the ninth century and is composed of carbo and sulfur as fuels with potassium nitrate, KNO3, as the oxidizer. Due to the large size of the sulfur and carbon fuel particles in black powder, complete combustion is unlikely and large amounts of smoke are produced during combustion. Black powder was the primary propellant used in military small arms and artillery prior to the nineteenth century and the smoke produced during battle often gave away positions and made visual signaling impossible.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Black powder (see introduction) was the propellant used in rifles and pistols during the 1860’s. Would it have been possible to use diphenylamine to detect gunshot residue on John Wilkes Booth after the assignation of President Lincoln? Why or Why not?
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