Whether it is a cherished annual festival or a casual celebration in your backyard, fireworks, which are scientifically known as pyrotechnics, help to make events more memorable by lighting up the sky with all kinds of amazing shapes and colors. However, while gazing up at the awe-inspiring bursts of fireworks in the sky, have you ever wondered what makes them appear so colorful and fantastic?
Fireworks are generally composed of three forms of energy release; light, sound, and heat. It is this rapid release of energy that produces such loud booms and flashes of light. Now, let’s talk about these three phenomena accompanying the burst of fireworks in a bit more detail.
Why the Loud Boom?
The boom, which is so commonly heard when a firework is set off, is produced by the excessive amount of energy being instantaneously released into the air, making it expand faster than the speed of sound. This rapid release produces a shock wave, which is why you hear a loud boom, something that has become a staple of firecrackers. Many interesting things happen when something travels faster than the speed of sound, such as the loud boom of aircraft flying through the sky.
Sparkling Lights and Heat
Much of what makes fireworks so immensely popular are the bright, colorful sparks they produce in the sky. Now, let’s find out how a seemingly ‘non-tech’ substance ends up projecting such a beautiful spectrum of colors across the sky.
The lights produced by fireworks are a result of salts being heated. I can probably guess what you’re thinking next: what do salts have to do with the colors of fireworks?
First off, these salts are not the same kind of NaCl you put in the foods you eat; no, we’re talking about certain kinds of special salts that, upon heating, are able to produce those colors. The most common metal salts used in fireworks are calcium chloride or sodium nitrate.
Gaining and Releasing Energy
Fireworks contain these metal salts because they are able to gather energy from an external agent (lighting the firework with a match). The atoms of these salts gain energy and, as a result, the electrons in the lowest energy state (the ground state) get rearranged very rapidly. Imagine throwing a bucket of water onto a pile of dirt; things begin to rearrange almost immediately! The same thing is true for fireworks!
As these electrons gain energy, they transfer to a higher-energy state (also referred to as an “excited state”, which is quite a literal description). Since these electrons are not meant to stay in that state forever, they quickly return to their original state, i.e., the ground state. However, as they come back to the ground state, they release energy. This particular energy falls in the spectrum of visible light, and voila! You see all those magnificent colors!
Different Energies = Different Colors
The energy that is released during the state transitions result in the colors that we see when a firework explodes. This energy, in turn, depends on the elements that make up the firecracker. Sodium salts, for example, release about 200 kJ/mol energy, which gives off a yellow color. Similarly, strontium salts and lithium salts give off red colors, calcium salts produce the color orange, barium compounds release green colors, and copper compounds produce different shades of blue (one of the most difficult colors to produce).
Handle With Care!
As marvelous as the different colors of firecrackers appear to our eyes, (even though for some, the boom is all they want from firecrackers), firecrackers should be handled with extreme care. Countless incidents occur, especially during festive times, when people get hurt, and in extreme cases, even killed, while handling fireworks
Celebrate your cultural festivals as much as you want, but never forget that you are actually dealing with a dangerous explosive. Fireworks are products of science and energy; they won’t be looking out for your safety, so you need to put your personal wellbeing at the forefront of your mind, no matter how much you want to admire the fireworks up close!