Fireworks light up the New Year’s sky with a symphony of brilliant colours, soft crackles, and bright sparks. While they seem magical, the chemistry behind their breathtaking displays is surprisingly simple and just as fascinating.
Fireworks have a simple mechanism and go back centuries. A standard firework consists of three components: fuel, oxidiser, and binder. The fuel stores energy as it is the source of electrons in the mechanism. It gets burned throughout the course of the explosion. This reaction -called combustion- occurs through the reaction of the oxidiser and the fuel. The oxidiser receives electrons, and upon this exchange, energy is released. The binder on the other hand, just holds everything together, like a staple. It keeps the mixture stable so the reaction can be controlled.
Additionally, there are two main types of fireworks: force-and-spark and flame. In force-and-spark compositions, the main ingredients are potassium nitrate, sulphur, and finely-ground charcoal. On the other hand, flame compositions may use the same ingredients as their main ones, with antimony being the addition.
Lastly, and most intriguingly, we have the mechanism behind the assorted colours. The arrangement of the electrons in the shells outside of the metal’s nucleus handles the absorption of the energy and the emission of different the emission of different wavelengths/colours of light. As the elements on the periodic table get heavier, the relative energy levels that are associated with the distribution of electrons change, which also changes the colour at which these elements emit light. This way, we have distinct colour combinations for the different material configurations.
To sum it up, fireworks actually have really simple mechanisms, and understanding the chemistry behind them is just as enjoyable as admiring their dazzling beauty. So, next time you gaze at the new year’s sky, remember that the fascinating festival of colours is not magic; it is chemistry in action.
Resources:
UPenn-Penn Today: https://penntoday.upenn.edu/news/chemistry-behind-fireworks
Britannica: https://www.britannica.com/technology/firework