What do you need to make a firework?

Bonfire Night is fast approaching: so what is the chemistry of fireworks?
31 October 2013


Remember, remember the fifth of fireworksNovemberGunpowder treason and plot.We see no reason, why gunpowder treasonShould ever be forgot!

So here's your quick fire science on gunpowder and fireworks just in time for Bonfire Night, with Kate Lamble and Simon Bishop.

- It's often said that the Chinese invented gunpowder about 2,000 years ago. The first firecracker was a gunpowder-filled bamboo stick.

- The recipe for gunpowder was perfected in Europe in 1560. It has remained mostly unchanged ever since. To make a firework you need five ingredients: an oxidizer, a reducing agent, regulators, binders and colourants.

- Oxidizers are molecules that split apart to release oxygen. They are typically metals combined with nitrogen or chlorine.

- The released oxygen is then used to burn a fuel, called a reducing agent. This burning produces hot gases, usually sulphur dioxide and carbon dioxide.

- The oxidant in gunpowder is potassium nitrate, which releases oxygen to help burn sulphur and charcoal. Gases then build up inside a container, and when they are suddenly released - boom!

- In fireworks, these gases are pushed down at the ground, firing the rocket up into the air instead of causing an explosion. There is then a second compartment full of gunpowder, oxidants and chemicals that give out coloured light.

- The third crucial ingredient is a regulating chemical, which speeds up or slows down the reaction depending on the desired effect -- sparklers need to burn quickly, for example, and the gases push out small lumps of burning iron or titanium, creating the sparks. Fireworks use everything from metal powders to cornmeal as regulators.

- Binder chemicals hold everything together. In sparklers, common binders are sugar or food glazes, dampened with water or even alcohol.

- To create light, fireworks are packed with metal salts. Different metals burn with different colours -- burning aluminium will give white light, oranges come from calcium, and green and blue colours come from burning copper.

- It's all of these ingredients that come together to make firework displays so exciting. But the world record for the most fireworks launched within 30 seconds might take some beating. In 2010 in the Philippines, it took just 17 seconds to launch nearly 126,000 rockets....

We hope you enjoy Bonfire Night fireworks this year! Just remember to stay safe - always read instructions, remember to stay well back, and never go back to a lit firework.


Add a comment