The presence of sulphur in gunpowder

Gunpowder, or black powder, is a mixture of potassium nitrate (oxidizer), charcoal (fuel), and sulfur. While charcoal is the primary fuel, sulfur is included because it undergoes exothermic reactions at relatively low temperatures. Specifically, sulfur melts at approximately 115°C and volatilizes to produce reactive gas-phase species that ignite easily. This process lowers the overall ignition temperature of the mixture, acting as a 'trigger' for the combustion of the charcoal and potassium nitrate. By lowering the ignition temperature, sulfur ensures faster and more reliable ignition of the powder. Although sulfur also contributes to the heat of the reaction and the speed of combustion, its primary chemical role in traditional formulations is to facilitate ignition at a lower thermal threshold than a simple charcoal-nitrate binary mixture would allow.