In the United States, celebrating our country's founding comes with two essential things: cookouts and fireworks. With the exception of New Year's Eve and New Year's Day, we are known for making some of the biggest spectacles of colored lights for the Fourth of July. From large displays held at the end of special events to a few sparklers going up after the sun goes down, it is hard to imagine a time when fireworks weren't lighting up the night. But beyond lighting the fuse and running as far away as possible, there isn't much discussion about the science (chemistry, to be exact) behind what makes the spectacle spectacular. Here are some things to know about fireworks that may be surprising.
Now, not all fireworks function the same way. Most fireworks have the same parts, but have slight variations that make them exciting. It all starts with some charcoal, sulfur, and potassium nitrate. Once a flame sparks, it'll ignite the sulfur. The sulfur will cover the charcoal and potassium nitrate and ignite them. For that reason, the container holding these three chemicals should have a hole to let the resulting explosion propel the firework into the sky before it can go up.
Once the fuse became a part of the equation, however, it allowed more time between when the firework gets lit and when an explosion would occur. With the introduction of the fuse also came the addition of "stars" to the original three chemical mixture. According to PBS, "stars" are small spheres or cubes made of metal salts, in a particular pattern. The stars are what cause the bursts of light in multiple shapes and colors in the night sky. Some fireworks are designed explode multiple times, each time in different patterns different colors.
In 200 B.C., during the Han Dynasty, fireworks were called "Baozhu". This word meant "exploding bamboo". They were called this because alchemists during this period would heat hollow stalks of bamboo until they got hot enough to explode. After 400 years, they advanced to cast iron shavings or steel dust to add shine. By 1830's this practice had made it all the way to Italy, but with some variations. Potassium chlorate was chosen, instead of potassium nitrate, allowing the materials in the firework to burn hotter, brighter, and this allowed for the addition of color. Firework makers in Italy chose chemical that would add the desired colors once the burned hot enough. For red, they used lithium and stronium. Barium made green explosions while copper brought blue. Sodium brought out the yellow while calcium made orange.
But America isn't the only country that loves to throw up those colored lights. The annual festival at Lake Biwa in Japan uses over 10,000 fireworks. The Eiffel Tower takes center stage in an amazing fireworks display honoring Bastille Day in Paris. Yanshui Beehive Fireworks Festival utilizes thousands of fireworks in Tainan City, Taiwan. In addition, festival attendees wear protective suits and helmets, just in case things get out of hand. However, the Guinness world record is held by Dubai in the United Arab Emirates. Back in 2014, 500,000 fireworks were shot from the Burj Khalifa building to bring in the New Year with style.
With another birthday for our country down (and hopefully many more to go!) it's a wonderful thing to come together and celebrate with those we love and the kind of beautiful displays that fireworks can create. As with most things, it's essential to remember the science that made things possible. And it is good to remember that these and even greater things can be done through chemistry in the future. In the meantime, let's light a spark for America!
Happy Fourth of July!
Greenberg, Alissa. “The Science of Fireworks.” PBS, Public Broadcasting Service, 2 July 2022, https://www.pbs.org/wgbh/nova/article/fireworks-chemistry-colors/.
Kuhne, Michael. “The Science behind Fireworks: 'Chemistry in Action'.” AccuWeather, AccuWeather, 23 June 2022, https://www.accuweather.com/en/weather-news/the-science-behind-fireworks-chemistry-in-action/433921.
“Nova Online | Fireworks! | Anatomy of a Firework (Non-Flash).” PBS, Public Broadcasting Service, https://www.pbs.org/wgbh/nova/fireworks/anat_nf.html.
The Science of Fireworks, https://www.ontariosciencecentre.ca/science-at-home/diy-science-fun/the-science-of-fireworks.
Staff, National Geographic, and Karen Gardiner. “These Are 12 of the World's Most Spectacular Fireworks Displays.” Travel, National Geographic, 2 July 2021, https://www.nationalgeographic.com/travel/article/fireworks-light-up-the-sky-across-the-world.
Waxman, Olivia B. “July 4th Fireworks History: How They Became a Tradition.” Time, Time, 3 July 2017, https://time.com/4828701/first-fireworks-history-july-4th/.