Fireworks. Everyone has seen them and/or used them. More recently, during Chinese New Year break, I watched as people bought fireworks by the box-loads and set them off with the excitement of 6-year old boy playing with an action figure he got for his birthday. As the constant sound of fireworks continued for days, even on the last night before school as I was trying to sleep (and as I write this post), I wondered how do fireworks work and why do we get so excited by watching them?
The mechanism of aerial fireworks is much like that of a rocket. In its simplest form, it is made up of two stages. The first is the propulsion section that is filled with gunpowder with a small hole in the bottom, which when combusts, releases the products carbon dioxide and nitrogen gas out of the hole to send the firework high into the air (this is sometimes replaced with compressed air, for safety reasons). The second stage contains the bits that you see as clouds of color. A fuse leads into the section that ignites the black powder, exploding the container (which is what you hear), sending the “stars” containing the salts in all directions giving off the colors as they do so. This is where the chemistry comes in. The colors are produced when atoms in the metal salts absorb the energy of the explosion, exciting the electrons. The electrons move to a higher-energy state and as they return to a lower-energy state that is more stable, they emit the light that we see (as demonstrated by the Bohr model). The amount of energy released depends on the compound used, and this in turn determines the color of light emitted. The colors range from red at the least amount of energy emitted to purple at the other end of what is the visible light spectrum.
So, now that we know how they work, why the fascination? If we were to use logic and reason as a way of knowing in this situation, we would find that it is quite pointless wasting both time and money to light explosives just to see the pretty colors that they create. After all, it is just a bunch of heated salt flying through the air after the explosion of a rocket. However, it is the creative side in us that causes this wonder of fireworks. It is a combination of sense perception and emotion that lead us to watch these shows of explosive art. Yves Pépin, a fireworks artist, puts it this way: “I think one reason people continue to be fascinated with fireworks is that they remain incomprehensible, even though people know how they work. They are a chain of chemical reactions that begins with a spark on the ground and ends in flashes of light several hundred meters in the air. But there is something sufficiently nature-defying so that it remains magical.” Thus, we appreciate fireworks much in the same way as we do art. It is the irrationally in us, that makes us spend millions on satisfying something that logic and reason just cannot explain.
Finally, what does this means for us IB Chem students? It means that the concepts that we are learning in class are not just to memorize and re-iterate for a good grade, but are actually used in real life in a very relatable way. As these fireworks displays continue for the next few days, until the people setting them off run out of money or the stores run out of fireworks (whichever comes first), we can look at these fireworks with the thought that we know the science behind them. Furthermore, this is an example of us asking why we do certain things and linking the science behind it. It is part of the quest to continually ask What? and Why?