Whether you’re soaking up the sun on a Miami beach this 4th of July, or you slipped outside of the 305 to celebrate, there’s no denying the patriotic sights and sounds of America’s Independence Day. From parades to backyard barbeques, the holiday isn’t complete without a quintessential pyrotechnic performance lighting the night sky. While these magical displays indeed spark a visual feast, there’s much more than meets the eye when it comes to the science behind fireworks.
At the University of Miami, associate professor of materials chemistry, Marc Knecht, doesn’t regularly focus his research on fireworks, but he agreed to share his knowledge of bio-inspired nanotechnology to help us understand what we see and hear when watching fireworks.
The Necessary Ingredients
A firework, Knecht tell us, is made up of a variety of chemicals packed into a container, which is usually cardboard. The main components include metal salts, for color; a combustible compound such as gunpowder, for the explosion; an oxidizing reagent, which provides the necessary oxygen for the explosion; and a binding compound to hold everything together.
Chemistry in Action
With each firework that dances across the night sky, the magic of science and chemistry are in full effect. Knecht explains that once heat is applied to ignite the firework, the oxidizing reagent fuels the exploding process, which ultimately causes the metals within the metal salts to burn. As the metal salts burn, the excitation and eventual relaxation of electrons on the metal are responsible for producing the vibrant firework colors that we have come to love. According to Knecht, not only is the explosion itself a true demonstration of chemical reactions, but the variation of brilliant colors can only be achieved from using metal salts that contain other elements such as sodium, calcium, or copper.
The Sound of Science
When it comes to the booms and fizzles that accompany the bright lights and colors, Knecht assures us that chemistry is certainly responsible. During the explosion, very hot gases are rapidly produced from the combustion and are forced to quickly expand. This reaction not only contributes to the broader pyrotechnic display, but also creates the loud sounds (don’t forget your ear plugs!) that are heard when experiencing fireworks. Because the gases expand faster than the speed of sound, the boom is actually a sonic boom, the same type that is typically heard from fighter jets.
Are you looking to get a glimpse of chemistry at work this 4th of July? We’ve compiled a list of places around the U where you can witness the art and science of fireworks.
If you find yourself near the Coral Gables campus on July 4, the City of Coral Gables Fireworks at the Biltmore Hotel is great option to view fireworks, listen to live music, and enjoy concessions. To help avoid traffic congestion, you can park at UM’s Pavia Garage or use one of the other free parking garages and take a free shuttle to the event. Another nearby family friendly celebration is Coconut Grove’s 4th of July Picnic and Fireworks in Regatta Park.
Looking to venture to the home of the UM’s Rosenstiel School of Marine and Atmospheric Science (RSMAS) campus? You’re in luck. The City of Key Biscayne hosts a red, white, and blue parade where residents compete to have the most patriotic float (or golf cart), view fireworks, and enjoy live entertainment.
Lastly, 4th of July in Miami wouldn’t be complete without Bayfront Park’s America’s Birthday Bash and Miami Beach’s Fire on the Fourth celebrations. Both events feature concerts, events, and of course, fireworks with picturesque views of Downtown Miami or Miami Beach.
With a fresh perspective on the science behind fireworks and a local’s guide to celebrations in and around the U, there are no limits to celebrating this week. From our ’Cane family to yours, Happy Fourth of July!
