The Chemical Technology behind Firework Explosions

During major celebrations, the evening sky usually lights up with brilliant explosions. It is amazing to see how pyrotechnics blow up into spectacular patterns of coloured fire in the sky. But have you ever wondered about the chemical technology that makes fireworks explode in captivating bursts? The secret lies in the chemicals that compose each kind of firecrackers.

They usually are composed of two stages that employ very different substances. The first stage uses a propellant, usually a combination of carbon and sulfur, which pushes the explosives up in the air. The second stage is a compartment that contains "stars", pellets of chemicals that, when ignited, produce intense light and create the distinctive colours and patterns. Each star contains five basic ingredients: a fuel that allows it to burn, an oxidiser to support the fuel combustion, a binder, a colour-producing compound, and a chlorine donor to intensify the flame's colour.

Different chemicals are used for different colours and effects. Here are some of the compounds that are commonly used in pyrotechnics:

Barium is used to create green colours in bursts. Aside from that, it also contains properties that stabilise volatile elements. Granules of potassium nitrate are utilised for purple colours as well as to oxidise the star. Sodium imparts yellow or golden colours. Sometimes, the sparks that this produces are so bright that they mask other explosions. Strontium salts give a red colour to the detonation. They also help stabilise the firecrackers. Calcium salts are mixed in the star to produce orange sparks.

Just think of the multitudes of compounds at work each time a pyrotechnic is launched into the air!

Essential Additions

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