The chemistry behind fireworks - WNEM TV 5

The chemistry behind fireworks

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MT. PLEASANT, MI (WNEM) -

The Fourth of July means food, fun and fireworks.

As the sky fills with the pyrotechnics, Central Michigan University chemistry professor Gabriel Caruntu explains the science behind the colors.

Fireworks are made up of five components:

  • An oxidizing agent: necessary to produce the oxygen required to burn the mixture. 
  • Black powder: used as fuel. 
  • A chlorine-donating compound: to help strengthen some colors.
  • A binder: to keep everything together.
  • A metal salt: to produce color. 

The color comes from different chemical elements and metal salts. When the salts are heated, tiny particles called electrons absorb the heat and are promoted to higher energy levels where they emit light, or various colors, at different wavelengths.

Violet or blue colors are produced at higher energies that correspond to shorter wavelengths. Conversely, orange and red colors — on the opposite end of the spectrum — are produced at lower energies and correspond to shorter wavelengths.

In case you were also wondering why fireworks are so loud, professor Caruntu has an explanation for that as well. The booms are the result of a rapid release of energy into the air. That causes the air to expand faster than the speed of sound. This rapid expansion produces a sonic boom.

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