We all love fireworks and they bring a lot of enjoyment to parties from birthdays to weddings. While the bursts of colour and the dazzling effects are often over in seconds, the craft that has gone into creating all that has taken quite a bit of chemistry.
So, if you’ve ever wondered how the colours are created, this guide will hopefully answer all of your questions.
All About Chemistry
The quick explanation behind firework colours is all about chemistry and how it is used when fireworks are built. As well as having a cartridge full of gunpowder to create the blasts, fireworks also have small pockets filled with different chemicals.
The chemicals in these little pockets are mainly metal salts and metal oxides, which cause the reaction to produce a mix of colours for our enjoyment. These pockets of chemicals are spread around the firework to provide the different colours and the heating gunpowder releases the chemicals into the air.
The atoms in these oxides and salts get heated by the gunpowder, which causes the electrons to rearrange. The rearrangement makes these electrons go from high-energy state back to low-energy state, during which the excess energy produced will emit light.
How Light Waves Work
You might know that light travels in waves. Exploiting the differences in the wavelength creates the differences in colour. The different chemicals used in fireworks are chosen based on the kind of wavelength the released energy produces.
Metal salts and oxides with shorter wavelengths, around 400 to 500 nanometres, are used to produce different shades of blue. The salts and oxides with longer wavelengths, around 600 to 700 nanometres, create the bursts of red and orange colours. Finally, the wavelengths that fall between this, 500 to 600 nanometres, produce yellows and greens.
Specific Compounds Behind the Colours
The chemical composition is naturally different for each colour. You’ll need quite a number of different oxides and salts in order to create the different colours. As you might have read from our previous post on the history of fireworks, the plethora of colours in fireworks has been quite a recent invention.
Here are the compounds used in fireworks to create certain colours:
- Red – strontium for dark, bright reds and lithium for dimmer reds
- Orange – calcium
- Yellow – sodium
- Green – barium together with chlorine producer
- Blue – copper together with chlorine producer
- Purple – strontium together with copper compounds
- Gold – charcoal, iron and lampblack
- White/silver – titanium, aluminium, magnesium and beryllium
Naturally by mixing and matching these chemicals, you can create all sorts of variations of the colours. By using chemicals, manufacturers are also able to add special effects and enhance the colours. For example, by adding antimony to the fireworks, manufacturers can create the glittery effect. In addition, a hint of calcium and the colour is deepened, while phosphorous adds the glow-in-the-dark effect to fireworks.
The exciting thing is that firework manufacturers are constantly researching new chemical compositions to come up with all sorts of stunning colours and effects. It will be interesting to see how the science behind fireworks develops and what sorts of amazing creations will we be able to see in the years to come!