The sulfur is gonna act as a catalyst in this reaction and that’s gonna lower the activation energy, which means that it’s going to take less heat to get this reaction going.So if I mix sulfur with the potassium nitrate and the charcoal, it should be much more explosive.So let’s test it out.Whoa.That was a lot bigger.So the sulfur really did increase the reaction.Now I’m gonna show you what it looks like when you actually put this in a firework.So here we have a firework that’s ready to go.It’s got a fuse at the bottom.It’s got a paper casing that’s going to hold the gunpowder in there and keep it together.And when I light this, it’s gonna shoot up into the air and it’s gonna explode in the sky, creating these beautiful shapes and colors.So let’s give it a try.Three, two, one. (fireworks popping)
Wow! I cannot believe the precision with that huge camera on there. Gene is gonna try to fly the FPV drone actually like through the fireworks as they explode. You ready Gene?
Gene: I think so.
Gene makes the channel called Potato Jet and he does tech reviews, but also lots of very filmic stuff.
Gene: Lot of drone work. Lately a lot of drone stuff. Okay. A lot of fast drone stuff. FPV drones. Like this one.
Are you willing to fly this into a firework as it’s exploding?
Gene: That’s the goal. If I can catch it, that’s the hope. But we set it up just for that. So I think we could get it. Sulfur starts reacting with the other ingredients at lower temperatures, giving off heat and acting like kindling. The classic recipe for gunpowder is 75% potassium nitrate, 10% sulfur, and 15% charcoal. To test how long it takes for fire to burn down about a meter of gunpowder, the experimenter used a homemade mixture and then compared it to store bought gunpowder. The chemical reaction that occurs in the combustion of gunpowder is complicated, and it creates a lot of smoke. When the gunpowder is confined, the reagents are forced into closer proximity and more energy is trapped, resulting in a bigger bang. The experimenter used 10 and 20 grams of black powder to get a bigger bang, which is essentially what a firework is. The shell of a firework is made out of cardboard and paper mache, and it is colorized so that the individual pieces can be seen better. The terms gunpowder and black powder are used interchangeably, but modern smokeless gunpowder is used in fireworks and is referred to as black powder. But, of course, I lost.It was like trying to outrun a bullet.
Have you ever seen a 4th of July firework display? Typically, you would see anything from two and a half inch to five inch aerial shells. For bigger displays, six inch and above shells are used, and in very special occasions, they can even go up to 12 inch, 16 inch and even larger! The biggest aerial firework ever was 1.44 meters wide, and it weighed about the same as a car.
To launch a firework into the air, black powder is used. In a typical shell, a baggie of black powder is placed underneath the shell which fires it out of the mortar to 800 feet in the air. For bigger shells, such as a 16 inch, pounds of black powder may be used to ensure the shell goes straight up. The shell is placed in a big plastic tube called a mortar.
When the firework explodes, the internal contents burn up before it reaches the ground, while the casing comes down in pieces. Therefore, a fallout zone or exclusion zone is necessary, where only the crew is allowed with all their protective equipment.
The pyro technician gets two bangs for every one the audience does. The first bang is when the mortar fires, and the second is when the shell explodes. Malfunctions are rare, but they do happen. To prevent shrapnel from being thrown everywhere, the shell is placed in a wooden rack with HDPE mortars.
The simplest fuse consists of cotton string soaked in black powder and then allowed to dry out. This is known as black match and it burns slowly. When encased in craft paper, the burn rate changes from a couple seconds an inch to anywhere from 30 to a hundred feet a second. This is known as quick match and it is used for the finale. I’m gonna light this little piece of black match and try to race the signal to the other end. However, I was not prepared for the explosions that followed. I was completely taken aback and asked, “What the heck was that?” I then realized that the force of the combustion products causes the quick match to whip around wildly. Even though the fuel and the oxidizer don’t need oxygen and air to burn, they do need heat and water is too good at conducting the heat away from the fuse, snuffing out the reaction. I even tested this with road flares, which stayed lit for a while underwater, but eventually the water stole the heat and put it out. There are special flares made for underwater applications, but they still have similar problems. Fuses are also used in fireworks, with a powder core and fiber wrap, which is typically lacquer coated and waterproof. The fuse is also used to light the time delay fuse inside the shell, so that it only explodes when it reaches its peak. We tested this underwater and it worked, with the fire progressing through the fuse. The fire is contained by the weaves of fibers and a layer of asphalt, providing the waterproofing. Both of us laughed when we figured out that the blue material in fireworks is usually made of rice hulls. We then talked about how the stars are made of black powder mixed with chemicals to give them different properties. We discussed how the primer composition is used to ensure ignition of all the stars and then transfer fire to the color composition. We were also amazed to learn that the colors of fireworks are actually thanks to quantum mechanics, where an element absorbs energy from the combustion and gives off light with a specific energy corresponding to a particular color. Finally, we talked about how copper ions give off blue light predominantly, which is why we get such a great blue color. What a thing of beauty! The colors that come from the electron transitions in the atoms and the molecules are what give fireworks their beauty.To get different colors, chemists mix up different salts and fuels and then coat the stars in layers.The stars are then set off with an electric match and the explosions are triggered by a button.It’s an amazing sight to see fireworks in the sky, and it’s even more amazing to fly a drone through them. Every time a KiwiCo crate arrives at our house, my kids get really excited. The contents inside provide a hands-on project that they can build with me, while learning about science, technology, engineering and design. The best part is that the crates contain everything needed to complete the project, so there are no additional trips to the store.
At KiwiCo, the crates are designed by experts and tested with kids before they are sent out. The subscriptions are a great value, usually around $20 per month, and they have nine different product lines for different age groups.
Working on these projects has become something that we do together as a family, and I really appreciate that. If you want to try it out, go to kiwico.com/veritasium to get your first month free. Purchasing single crates is also an option through the KiwiCo store, making them great gifts.
I want to thank KiwiCo for sponsoring this video and I want to thank you for watching.