July 4, 2014
The Science Of Celebrating The Fourth (Of July)
Who does not love a good fireworks show? When I was little, I remember going out to a friend’s farmhouse well out of town every Fourth of July with a number of people from the community to watch a grandiose fireworks display. Though there were always a few duds, the show was always spectacular. The kids — including myself at the time — would run around with the sparklers, pretending they were magic wands or lightsabers or whatever else our young minds would envision, then as it became truly dark, the sky would explode with a wondrous display of color and sound.
Nowadays, I do not enjoy these shows as much. Thanks to a level of acute hearing, the sound of the exploding fireworks can be painfully deafening and, honestly, I miss the days of going out to the farmhouse and celebrating with the people I knew. The family that used to host them has long since stopped doing so and I no longer live in the area anyway. There are still shows to see, of course, but they lack the same sense of fun, community, and family that I grew up with. Ah, nostalgia…
Still, that does not stop the science behind those incredible light shows from being a source of endless fascination. So, in celebration of the Fourth of July, I thought I would share some of that incredible science with you. As explained by John Conkling, chemistry professor at Washington College in Chestertown, Maryland and author of the textbook titled The Chemistry of Pyrotechnics: Basic Principals and Theory, fireworks are an incredible science. It’s “chemistry in action,” as he describes it.
So what goes into making fireworks? Well, firstly, every firework has a chemical in it that is rich in oxygen — an oxidizer. These are chemicals like potassium nitrate, which is used in making black powder, potassium perchlorate, which is used in a lot of different color compositions, or strontium nitrate, which is used to make the bright reds we see in many fireworks. In addition to this, fireworks need a fuel source that will combine with the oxidizer to produce heat and flame. Most commonly used for this are things like sulfur, charcoal, aluminum powder, or magnesium powder. These are all used in different quantities to produce different heat outputs and burn rates, all depending on the exact sort of effect the pyrotechnician is going for.
All right, we have our chemicals. What’s next? Next, they are all put together into what is called an aerial shell. Aerial shells are cardboard casings that hold all the different chemicals inside, with a pocket of black powder at the bottom to act as propellant, as well as a time fuse that determines how soon after take off that the firework will erupt. Inside the spherical casing, there is a black powder bursting charge at the core, which is what causes the firework to go “boom” up in the sky, and numerous little pellets no smaller than a pea or bigger than a marble that hold all the different color chemicals in them, which create that spread of color you see when a firework goes off.
Now we know what fireworks are made up of and how they come together. The next step is getting them into the air. This is done via mortar tube. Yes, you read this right. Mortar tubes. Kind of interesting to think about, right? How we remember the gaining of our nation’s independence via firing things out of a mortar launcher? I could go more into the symbolism of that, but I choose not to. For now, let’s just keep our focus on the fireworks. When it is time for the show to begin, a fuse (or electric signal, depending on the type of launcher used) is used to ignite the firework, blasting it out of the mortar tube and into the sky. Then, that time fuse mentioned earlier goes up into the body of the firework and ignites the core, sending out those now burning pellets, which create all those incredible colors, depending on what chemicals are housed in them.
And so there you have it, a brief introduction into the science of fireworks. If you would like to hear more about this from the mouth of Professor Conkling himself, you can watch his video on the matter below. I highly recommend it, as the man is both very educational and highly entertaining.
I hope all of you out there have a safe and happy Fourth of July and, when you see those incredible displays of color up there in the sky above, take a moment to remember the science behind them.
After all, it’s “chemistry in action.” Truly a Miracle of the Modern.
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