Tag: bonfire night

Chemistry of Fireworks – Bangs, Crackles & Whistles

The Chemistry of Fireworks: Bangs, Crackles & Whistles

Infographic on the chemistry behind firework bangs, crackles and whistles. Bangs are produced by the ignition of an explosive mixture, usually an oxidiser, sulfur and aluminium. Compacted, confined gunpowder also produces a loud bang. Crackling fireworks originally used a mix of lead tetroxide and magnallium, but now bismuth compounds are more commonly used. Whistling fireworks use aromatic organic compounds such as gallic acid tightly packed into a tube with oxidisers. Small explosions caused by these compounds lead to oscillations in the gases produced, creating a standing wave in the tube that gives a whistling effect.
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With the 5th of November approaching, the distant reports of early fireworks displays can already be heard in the evenings here in the UK. Discussion on the chemistry of fireworks usually centres on the compounds used to generate their array of colours, but there’s a whole lot of chemistry behind the sounds they make too. Here we take a brief look at some of the ways in which pyrotechnic chemists give fireworks their characteristic bangs and screeches.

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