Spark, Spark! The Chemistry of Fireworks
Ever wondered what causes those fancy fiery works of art shine so bright? The science of how fireworks operate is actually simple. And we’ll find out.
Pyrotechnics, especially fireworks, operate on a simple theory called combustion. Combustion involves the use of oxygen, that why you can’t light a fire in an airtight setup. It also involves the release of energy, in form of heat and/or light energy.
For a firework to burst into an array of spectacular colors, it must contain the following:
- Fuel. Must contain either charcoal or thermite alongside the common blackpowder.
- Oxidizing Agents. These produces the oxygen needed to burn the mixture. These are either nitrates, chlorates, or perchlorates.
- Reducing Agents. These react with the O2 released by the oxidizing agent/s to produce hot gases, and can also be used to control the speed of the reaction. Sulfur and charcoal are the most common reducing agents used.
- Metals. These also control the speed of reaction. Larger surface area = faster reaction rate.
- Coloring Agents. They give color to the firework. Strontium (Sr) produces red, Copper (Cu) produces blue, Barium (Ba) produces green, Sodium (Na) for yellow, Calcium (Ca) for orange, and Gold (Au) or Titanium (Ti) for an iron-ish color. These elements when heated, produces excess energy in form of light, and the higher the temperature, the shorter the wavelength.
- Binders. These hold the mixture in a paste-like texture. The most commonly used binder is dextrin, though parson is also used.
So, fireworks are actually maelstroms of excess heat energy released by different reactions occurring inside the canister. So as we welcome 2014, let us appreciate these brilliant works of both art and science. Cheers to a new year!