Happy 4th of July!
One of the coolest parts of celebrating the United States’ independence are the beautiful fireworks shows.
Fireworks were invented about 1,400 years ago in China. 800 years ago, Marco Polo (an Italian merchant) is believed to have brought them to Europe, and form there they made their way around the world.
But have you ever wondered how they work?
The main science that makes fireworks as big and beautiful as they are is chemistry.
When fireworks go off, you’re witnessing chemical reactions! It is made with fire, which is what you can see when a chemical reaction called combustion happens.
What is a chemical reaction?
A chemical reaction is a process in which one or more materials are converted to one or more different materials. When you cut a tomato it is still a tomato- no new materials were formed. But when you burn wood - it is a chemical reaction as new materials is formed - ash.
Fire is a chemical reaction between oxygen in the air and fuel. Fuel can be many different things, including wood or gas. For example, when you light a match, it causes a reaction between oxygen and the wood. However, there is also red stuff on top of the match, known as phosphorus sulfide. What does that do? It is the igniter. To start a fire, you need heat along with fuel and oxygen. When you strike the match on the side of the matchbox, it causes a great deal of heat, which then causes the ignition of the fire.
This chemical reaction is very powerful, and can be used in many ways. For instance, the gas you pump into your car is fuel. When it combusts, it creates lots of energy to power your car, which is why they can go so fast! It also creates lots of heat. After you have been in a car for a long time, you may feel that heat if you touch the front of your car, where the engine is. (Don’t try this without an adult!) This same reaction is why planes can fly, trains drive, and why boats can sail the ocean.
A very similar chemical reaction can be used to cook! When you turn on a gas stove, you may hear a clicking sound. That is the ignition spark trying to light the gas. When it lights, you see the blue flame coming out, you hear a quick rumble, you can smell the gas, and you can feel the heat. The very high heat can be used to heat up food in a pot or pan.
Fireworks are very similar to regular fire caused by a match.
What makes the fireworks explode so beautifully compared to match is the difference in fuel, and certain chemicals that are added to create the color.
A firework needs key components to work:
An oxidizer is a type of chemical that a fuel requires to burn. Most oxidizers on Earth use oxygen, which is very common in our atmosphere. The most commonly used oxidizers are nitrates, chlorates and perchlorate.
The second component, fuel, is gunpowder. When set off, the fuel combines with the oxygen released by the oxidizer, breaking the fuel. This releases all the energy that’s stored in those chemicals and Boom! Explosion.
To ignite this chemical reaction, all you need is a bit of fire.
So how does it work:
STEP 1: Ignite the gunpowder and create the chemical reaction that causes gas to expand very quickly. It burns all the way down to the bottom and hits the “lift charge” and off into the sky it goes! The process takes a little time and allows whoever lit the firework some time to get out of the way! You don’t want to be near a firework when it goes off.
STEP 2 - LIFTOFF! The burning fuse lights a larger patch of gunpowder at the bottom of the firework. That explosion carries the rocket into the sky!
STEP 3 - Finally, there’s another bundle of gunpowder that’s packed into the firework’s body, called the burst charge - this is the big show. This is what ultimately causes the firework to burst apart! Beautiful Explosion. Chemicals are added to create color, and different chemicals will create different reactions. For instance, if you want a red firework, you need to use a compound with the chemical strontium. You’d use barium to make green, copper to make blue, and sodium to give you a yellow-orange color.
Vocabulary
combustion - a chemical reaction that produces heat and light
Chemical Reaction - a process in which one or more materials are converted to one or more different materials
Pyrotechnics - the art of making or displaying fireworks
Pyrotechnicians - people who work with fireworks!