In 1040 CE, Chinese alchemist Tseng Kun-Liang published the first gunpowder formula for use in weapons ... needed to be 75 % potassium nitrate in order to explode. The typical modern formulation for ...

All kidding aside, the invention and proliferation of gunpowder had a profound effect on the world. Here you can see just how easy it is to make with chemicals that are common in our modern world.