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NGSS: Core Idea: PS1.B
CCSS: Writing: 7
TEKS: 6.5A, 6.5C, 7.6A, 8.5E, C.4A
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The Science of Sparklers
How a twinkling chemical reaction helps you celebrate Independence Day
AS YOU READ, THINK ABOUT the purpose of each element or chemical involved in the reaction that powers sparklers.
Summertime means Fourth of July festivities. Some communities celebrate with fireworks displays. But there’s also a fiery phenomenon people can hold right in their hands—shimmering sparklers. When lit, these sticks shoot out showers of colorful embers. “There is a lot of high-energy, high-temperature chemistry going on as that sparkler burns,” says John Conkling. He’s a retired chemist and former director of the American Pyrotechnics Association, an organization for members of the fireworks industry.
To make a sparkler, a wire—usually made of the element iron (Fe)—is dipped into a wet paste and allowed to dry. The paste is made of three things: a metal fuel that provides energy, an oxidizer that allows the fuel to burn, and a glue-like binder to hold everything together. Some sparklers also contain colorants, so they glimmer with different hues. The only thing you need is a flame to set the chemical reaction in motion. Read on to find out more.
Summer means Fourth of July parties. Crowds will gather to watch dazzling fireworks burst in the sky. But people can also hold a fiery wonder right in their hands. It’s a shimmering sparkler. When these sticks are lit, they produce showers of colorful sparks. “There is a lot of high-energy, high-temperature chemistry going on as that sparkler burns,” says John Conkling. He’s a retired chemist and former director of the American Pyrotechnics Association. That’s an organization for members of the fireworks industry.
To make a sparkler, a wire is dipped into a wet paste and allowed to dry. The wire is usually made of the element iron (Fe). The paste contains three things. A metal fuel provides energy. An oxidizer allows the fuel to burn. And a glue-like binder holds everything together. Some sparklers also contain colorants. That’s how they shimmer in different shades. All you need is a flame to start the chemical reaction. Read on to find out more.
Oxidizer: All fuels need oxygen (O) to burn. So sparklers have an oxidizer, which breaks down and releases oxygen atoms when heated. “If metal powders are around to act as fuel, the freed oxygen atoms will attack them, and you’ll get a continually burning fire,” says Conkling. The most common oxidizer in sparklers is nitrate, a compound that contains nitrogen (N) and oxygen.
Oxidizer: All fuels need oxygen (O) to burn. So sparklers have an oxidizer. It breaks down and releases oxygen atoms when heated. “If metal powders are around to act as fuel, the freed oxygen atoms will attack them, and you’ll get a continually burning fire,” says Conkling. The most common oxidizer in sparklers is nitrate. It’s a compound that contains nitrogen (N) and oxygen.
Sparks: A burning sparkler can reach temperatures of 1,000°C to 1,600°C (1,832°F to 2,912°F)! But each spark has such a small mass—amount of matter in an object—that it doesn’t release much thermal energy, or heat. That’s why you can enjoy the handheld light show without getting burned. Just be sure not to touch any part of the superhot glowing stick except its handle.
Sparks: A sparkler can burn as hot as 1,000°C to 1,600°C (1,832°F to 2,912°F)! But each spark has only a tiny mass. That’s the amount of matter in an object. So it doesn’t release much thermal energy, or heat. That’s why you can enjoy the mini light show without getting burned. Just be careful! Don’t touch any part of the superhot glowing stick except its handle.
Fuel: A fine powdered metal, often aluminum (Al), serves as fuel for the reaction. The aluminum melts as it burns and begins to glow. Since the iron at the sparkler’s center has a higher melting point than aluminum, the wire remains solid. But as it’s heated to high temperatures, tiny bits of iron ignite and fly off as sparks. “They’re ejected off the sparkler wire as these little dabs of light that twinkle,” explains Conkling.
Fuel: The fuel for the reaction is a fine powdered metal. Often, it’s aluminum (Al). As it burns, the aluminum melts and begins to glow. The iron at the sparkler’s center has a higher melting point than aluminum. So the wire remains solid. But as it gets hotter, tiny bits of iron catch fire. They fly off as sparks. “They’re ejected off the sparkler wire as these little dabs of light that twinkle,” explains Conkling.
Binder: A binding material is needed so that the flammable fuel and oxidizer mixture sticks to the wire. Dextrin, a type of starch, is a common binder for sparklers. But it also serves a second purpose. This combustible material burns extremely slowly, which helps keep the sparkler from fizzling out too soon. “Without that binder, you wouldn’t get anywhere near the quality effect you see,” says Conkling.
Binder: A binding material is also needed. It makes the flammable fuel and oxidizer mixture stick to the wire. Dextrin is a common binder for sparklers. It’s a type of starch. But it also serves a second purpose. This flammable material burns extremely slowly. That helps keep the sparkler from fading out too soon. “Without that binder, you wouldn’t get anywhere near the quality effect you see,” says Conkling.
To make sparklers that glow different colors, manufacturers add salts that contain specific metal atoms. As the sparkler burns, negatively charged electrons in the metal atoms absorb energy. This extra energy is released as different wavelengths, or colors, of light.
SHUTTERSTOCK.COM
Calcium (Ca) creates an orange color
Strontium (Sr) releases red light
Barium (Ba) emits green
Copper (Cu) causes a blue hue
Sodium (Na) glows yellow
COMMUNICATE INFORMATION: Describe the chemical reaction that allows sparklers to sparkle, in your own words.
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