Fourth Of July: The Art And Science Of Fireworks

Why do fireworks displays attract so many people? There are many answers to this question, but most people simply enjoy the bright explosions of light, colour and sound. Others enjoy being surprised by the shape and colour of the fireworks bursts. These shapes and colours do not happen by chance. They are deliberately produced by a careful combination of art, chemistry, physics and math

Fourth Of July - The Art And Science Of Fireworks
Fourth Of July – The Art And Science Of Fireworks 

The displays that dazzle revellers on the Fourth of July and many other holidays are the result of chemists and other researchers working to create and choreograph pyrotechnic theatre in the night sky.

What are fireworks and how do they work?

A firework is essentially a missile designed to explode in a very controlled way with bangs and brightly coloured light bursts. An aerial fireworks burst is produced by launching a fireworks shell high into the air, where an explosion occurs. This explosion propels brightly burning particles in many directions. 

The evolution of fireworks

Fireworks were probably invented in China more than 2,000 years ago. There, people found that when they tossed a bamboo stalk into a flame, it exploded. As air pockets in the bamboo overheated, they’d expand enough to shatter the stalk. The sudden bang would supposedly ward off evil spirits.

The innovation in fireworks
The innovation in fireworks

Centuries later, chemists added a crude type of gunpowder to these bamboo bomblets. That made the bangs bigger. Somewhere along the line, people found that adding metal powders and shavings to their mixtures made things sparkle. Later, they developed rockets by packing these materials into stiff paper tubes.

The science of fireworks

Chemistry

An exploding firework is essentially a number of chemical reactions happening simultaneously or in rapid sequence. When you add some heat, you provide enough activation energy which contributes as a kick-start a chemical reaction, to cause solid chemical components inside the firework to react with oxygen in the air and transform into other chemicals, producing smoke and exhaust gases such as carbon dioxide, carbon monoxide, and nitrogen in the process. 

Chemistry holds the secrets to the colour of a fireworks burst. The colours that you see in the sky are determined by metallic compounds that are deliberately added in very small amounts to the stars when they are manufactured. As the stars burn, the metal atoms absorb energy, become excited and emit a specific colour of light. 

Different metal compounds give different colours. Sodium compounds give yellow and orange, for example, copper and barium salts give green or blue, and calcium or strontium make red.  Coming up with a new colour can take a lot of time and involve a lot of trial and error. But by choosing and mixing chemicals in the right proportions, chemists can make a shell that will display almost any colour imaginable

Physics

According to a basic law of physics called the conservation of energy, the total chemical energy packed into the firework before it ignites must be the same as the total remaining in it after it explodes, plus the energy released as light, heat, sound, and movement.

The law of physics also explains why the shooting of fireworks into the air. The charge is little more than a missile. As it burns, the firework is powered by Newton’s third law of motion, in exactly the same way as a space rocket or jet engine. 

When the powder packed into the charge burns, it gives off hot exhaust gases that fire backwards. The force of the exhaust gases firing backwards is like the blast coming out from a rocket engine and creates an equal and opposite force that sends the firework shooting. 

Different types of fireworks

All fireworks function in roughly the same manner, combining the strength of a missile with the splendour of burning metallic compounds. However, there are still many distinct forms of fireworks. The ones mentioned above so far called rockets or skyrockets and produce the most spectacular displays high in the air. Catherine wheels and pinwheels work closer to the ground. 

Catherine wheels
Catherine wheels

They put a number of tiny pyrotechnics around the edge of a wooden or cardboard disk and spin it around as they blast them off. Roman candles blow out a series of small fiery explosions from a cylinder every so often. Firecrackers are fireworks designed to produce sound rather than light and they’re often incorporated into the upper effects of rockets.

Stay safe with fireworks

Fireworks give joy and pleasure to many millions of people every year, but they have to be treated with the utmost respect because they are extremely dangerous. If you get too near, it can severely burn you, disfigure you for the rest of your life or even kill you. Every year, errant pyrotechnics wreak millions of dollars in property damage, and there’s also the grief that fireworks bring to dogs to consider.

As a result, several nations have laws prohibiting the sale and usage of fireworks. If you’re going to use fireworks, make sure you read and follow all of the safety instructions carefully. Why not entrust the handling of fireworks to someone else? Attend a well-organized and controlled municipal show to have all the enjoyment of fireworks without the risk.

Conclusion

The Fourth of July fireworks display is a great opportunity for you to apply this knowledge into reality. You can study the different types of bursts and imagine how they might have been accomplished.  

Just imagine if fireworks didn’t exist and someone suddenly suggested the idea of allowing people to fire lots of explosives into the air! Thankfully, this is not the case and we may continue to marvel at the brilliant enchantment of these colourful aerial displays whenever we feel like having a fun outdoor event.