Science at home: Festivities and Fireworks!

The festive season is just about upon us, which means lots of food, friends, family, and FIREWORKS!

Fireworks have lit up our skies for hundreds of years, to celebrate and commemorate special occasions like New Year.

It’s generally believed that fireworks originated in China around 1,200 years ago when Chinese alchemists were trying to find the recipe for eternal life. They happened to mix together potassium nitrate, sulphur and charcoal – which created basic gunpowder that made a bit of a pop. Over the centuries, fireworks have been enthusiastically taken up around the world, and evolved from gunpowder packed into bamboo stalks thrown onto a fire, to the rockets with fuses launched into the sky today. They’ve also gone from being used as bombs and cannons in battles, to being used for entertainment and celebrations.

Today, fireworks consist of a series of individual pods (called ‘stars’) of about 3cm in diameter, each packed with gunpowder. Each star ends up being one dot in the final fireworks explosion. The stars are housed in a tube, which has a fuse sticking out – when the fuse is lit, it ignites the gunpowder and the explosion begins!

Fire needs fuel, heat and oxygen to burn.  If you add more oxygen, the fire gets hotter, brighter and burns faster.  Sulphur and charcoal make up the fuel in fireworks, and potassium nitrate is an extra source of oxygen – it’s an oxidiser.  This is why fireworks are much brighter and more explosive than candle or match flames.

We have 19th century Italy to thank for our coloured fireworks.  The Italians started adding trace amounts of metals (and other ingredients) to enhance the brightness of fireworks and change the shapes. They also introduced an array of colours by adding metal compounds like copper, sodium or barium to produce blue, yellow or green fireworks.  Different elements absorb and emit slightly different amounts of energy – so when you change the metal, you’ll make the firework emit different light colours.

If you’re too far away to see the fireworks this summer, you can always get some sparklers from a supermarket.  Sparklers are made with chemicals that are very similar to fireworks – but in much smaller amounts, so that they’re not so dangerous to hold.  You should still be careful with them, though!

If fire and fireworks are really fascinating for you, you might want to check out the Chemistry Major in our Bachelor of Science.

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