Q: What gives fireworks their colors?

Fireworks are made with the same main basic components:
• Fuel- gives the firework it’s burning power
• Oxidizer- provides oxygen for the fuel to combust
• Colorants- makes the colors
• Binder- keeps pellet together
• Chlorine donor- reacts with the colorant to strengthen color

So the colorants give the firework a pretty hue. But what exactly are the colorants?

The colorants are metal salts, which are ionic compounds that contain a metal. When the colorant burns, the electrons on the metal take on energy from the heat or flame and become “excited”- they have a higher energy than their normal ground state. This excitation is temporary. Eventually the electrons “relax,” releasing the extra energy.

In the case of these colorants, this released energy comes in the form of visible light, one type of electromagnetic radiation. The visible light emitted has a specific wavelength, which corresponds to a color. The color emitted depends on the identity of the metal in the colorant. (In fact, scientists can use an analytical technique called a flame test to qualitatively determine the presence of some elements.)

Periodic-Table-Fireworks.jpg

The color can be enhanced using something called a chlorine donor. Some of the brightest colors come from metal chlorides. However, metal chlorides tend to be hygroscopic, absorbing moisture easily, which would destroy the firework’s ability to catch on fire- not a great quality for fireworks. To get around that, metal salts and chlorine donors are mixed together. During combustion, the metal and chlorine combine in a vapor that, when burned, creates a brighter color than if only the metal salt was used.

You gotta love pyrotechnics.

Keep calm and science on.

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