The Fourth of July is almost upon us, and millions will gather to uphold the great American tradition of cooking out on the grill, drinking beer, and watching some big ol' fireworks.
If you've ever been curious about how fireworks actually work, allow us to run you through some of the basic, yet precisely timed, chemistry that allows these spectacular light shows to occur. Basically, all fireworks boil down to a relationship with an oxidizer (an oxygen-rich chemical that will burn) and a fuel (to feed the combustion of the oxidizer).
All aerial shell fireworks start the same way, with a lighting of a fuse. The shell itself is generally made out of cardboard, though it has distinct inner compartments to keep the different chemicals separated, controlling when the reactions take place.
The fuse is lit either manually or electronically using a wire, depending on the size of the show. The lit fuse just buys some time before it ignites the gun powder (or black powder) that propels the shell out of a mortar tube and into the sky.
By the time the black powder has burned up, the aerial shell is as high as it needs to be in the sky, and a time fuse leads into a chamber that is also filled with black powder.
This time, the black powder acts as a bursting charge rather than a propellant. The powder used in the bursting charge is pea-sized, opposed to the fine propellant, which makes the combustion more violent (and thus, a heck of a lot prettier).
The main part of fireworks that the average person cares about is the gorgeous, sparkly part that we can actually see. The visible part of fireworks are caused by little balls called stars, which are placed inside the exploding black powder.
The shape of the explosion is determined by how the stars are arranged inside the black powder, and there are a number of ways to tweak the overall effect of the show by manipulating the size, position, and chemical makeup of the stars.
The color of the explosion itself is set by which element is used as an oxidizer in the reaction. Strontium, for instance, creates red fireworks, while barium burns green, and copper creates bright blue bursts.
Want to know more about the chemistry that goes into fireworks? Check out the video below:
[Header image: maf04]