Gunpowder or black powder is of great historical importance in chemistry. Although it can explode, its principal use is as a propellant. Gunpowder was invented by Chinese alchemists in the 9th century. Originally, it was made by mixing elemental sulfur, charcoal, and saltpeter (potassium nitrate). The charcoal traditionally came from the willow tree, but grapevine, hazel, elder, laurel, and pine cones have all been used. Charcoal is not the only fuel that can be used. Sugar is used instead in many pyrotechnic applications.
When the ingredients were carefully ground together, the end result was a powder that was called 'serpentine.' The ingredients tended to require remixing prior to use, so making gunpowder was very dangerous. People who made gunpowder would sometimes add water, wine, or another liquid to reduce this hazard, since a single spark could result in a smoky fire. Once the serpentine was mixed with a liquid, it could be pushed through a screen to make small pellets, which were then allowed to dry.
How Gunpowder Works
To summarize, black powder consists of a fuel (charcoal or sugar) and an oxidizer (saltpeter or niter), and sulfur, to allow for a stable reaction. The carbon from the charcoal plus oxygen forms carbon dioxide and energy. The reaction would be slow, like a wood fire, except for the oxidizing agent. Carbon in a fire must draw oxygen from the air. Saltpeter provides extra oxygen. Potassium nitrate, sulfur, and carbon react together to form nitrogen and carbon dioxide gases and potassium sulfide. The expanding gases, nitrogen and carbon dioxide, provide the propelling action.
Gunpowder tends to produce a lot of smoke, which can impair vision on a battlefield or reduce the visibility of fireworks. Changing the ratio of the ingredients affects the rate at which the gunpowder burns and the amount of smoke that is produced.