With Independence Day upon us this week, the fireworks stands are popping up all over town. With the dry weather and heat wave many are experiencing this year, I am confidant many cities will be enforcing strict prohibitions against fireworks. Why not then take the time to explore the science of fireworks and perhaps try making a few simple ones yourself?
Learn about the science of fireworks with this awesome video. How do fireworks work? Where do the cool colors come from? What makes the big explosions?
Creating firework colors requires considerable art and application of science. Excluding propellants or special effects, the points of light ejected from fireworks, termed ‘stars’, generally require an oxygen-producer, fuel, binder (to keep everything where it needs to be), and a color producer.
The bright colors visible when fireworks explode are a result of pyrotechnic stars —pellets of chemicals that generate certain colors or produce sparking effects when burned. When the bursting charge is ignited, the main fuel explodes first, transferring energy to the colorant chemicals, which prompts these chemicals’ electrons to move into an excited state. Then, moments later, when the colorant chemicals cool and the electrons fall back to their base state, they release the extra energy as colorful radiation when they are flying through the sky. The specific color depends on the chemical:
To achieve unusually-shaped fireworks, such as double-rings, hearts or stars, technicians pack the fuel and colorant chemicals inside a tube in different formations. Chemists design fireworks to burn as slowly as possible, rather than explode rapidly – a slower burn means that a visual effect will last longer and cover a greater area of the sky. To achieve this, the fuel and oxidizer chemicals used are relatively large-grained, about the size of a grain of sand. Additionally, chemists avoid mixing the fuel and oxidizer together thoroughly, making it more difficult for them to burn.
If you wish to delve into the science of fireworks even further, consider undertaking flame photometry experiments. Rainbow Fire, is an exciting activity kit that you may wish to consider; it is available for purchase at Science Buddies. The necessary materials and the experimental procedure are outlined for you on their website. Of course, adult supervision is required. The four chemicals used in the kit are:
- Copper sulfate
- Strontium chloride
- Boric acid
- Sodium chloride
Things to Ponder
- How are the colors produced by a chemical when it burns related to the atomic structure of the chemical?
- What is flame spectrometry and how is it used by physicists and chemists?
- How does this science project relate to what astronomers do when they are trying to identify the atomic makeup of a star?
- What are metal ions? In the chemicals used in this science project, which elements in the compounds are metals?
Black Snake Fireworks
Do you remember watching long carbon worms emerge from growing tablets our parents lit with matches on the 4th of July? For a simple do-it-yourself recipe, a homemade black snake is sure to delight.