The sulfur helps lower the activation energy, so you need less heat to get the reaction going and it’s much more explosive.
I cannot believe the precision with that huge camera on there. Gene makes the channel called Potato Jet and he does tech reviews, but also lots of very filmic stuff. Lately a lot of drone stuff. Gene was willing to fly an FPV drone into a firework as it exploded. We also tested out the earliest known recipe for gunpowder. It involves three ingredients that you can find out in nature: potassium nitrate, sulfur and honey. When heated up, it would spontaneously catch fire. People figured out that a better fuel was charcoal, which contains microscopic pores that enables the reactants to mix much better. Adding sulfur helped lower the activation energy and made it much more explosive. Sulfur starts reacting with the other ingredients at lower temperatures, giving off heat and acting like kindling. The quintessential recipe for gunpowder consists of 75% potassium nitrate, 10% sulfur, and 15% charcoal. To test how long it takes for fire to burn down about a meter of this homemade gunpowder, a comparison was made to store bought gun powder from a factory. The chemical reaction that occurs in the combustion of gunpowder is complicated and creates a lot of smoke. To achieve an explosion, gun powder must be confined in a tight vessel. Experiments were done with 10 and 20 grams of black powder, and it was noted that fireworks consist of a shell with a lot of gunpowder inside. The shell is made out of cardboard and a form of paper mache with craft paper and glue. But that’s impossible.It’s just too fast.
Have you ever seen a 4th of July firework display? The standard size you’ll see is usually from two and a half inch up to five inch. For bigger displays, such as six inch and above, they are usually used for huge properties or on a barge. But they can go even bigger than that, up to 12 inch, 16 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, the way it’s done is with black powder. In a typical shell, you’ll have a baggie of black powder that’s underneath the shell, and that acts to fire the shell out of the mortar to the 800 feet in the air. Shells as large as 16 inch can use literally pounds of black powder underneath them to ensure the shell goes straight up. It’s placed in a big plastic tube called a mortar.
The internal contents of the firework will burn up before it reaches the ground, but the casing will come down in pieces. That’s why there’s a fallout zone, or exclusion zone, where only the crew is allowed with all their PPEs because you do get debris that comes down.
It’s rare, but firework malfunctions do happen. To prevent this, a pyrotechnician will use quick match, which is cotton string soaked in black powder and encased in craft paper. This has the same effect as containing the black powder, trapping in the heat and reagents, so the reaction goes much faster. This is how the finale is shot so quickly - it’s not actually pushing buttons that quickly. I’m going to light this little black match and try to race the signal to the other end. Unexpectedly, the force of the combustion products causes the quick match to whip around wildly. Even though these fuses contain the fuel and the oxidizer, they are not waterproof. Water is too good at conducting the heat away from the fuse, causing it to fizzle out. We tested it underwater and it was able to stay lit for a while, but eventually the water got in there and stole the heat. There are special flares made for underwater applications, but even those have similar problems. Inside a firework, a quick match flashes and ignites the black powder lift and a time fuse. This time fuse keeps the combustion contained inside it so the firework only explodes when you want it to. We tested the time fuse underwater and it was able to stay lit, showing how the fire was progressing through it. Eventually, it spit out the end, which is all that is needed to ignite the core of a firework. Both of us laughed as we discussed how rice hulls, coated with black powder, are used to create a very granular powder in the center of the shell, allowing the flame to propagate quickly and create an overpressure to blow the shell open. We then discussed how the points of light in a firework are actually quite small, but look bigger because they are so bright. We then discussed how a drone can be tricky to fly in the dark and the colors of fireworks are actually thanks to quantum mechanics. An element absorbs energy from the combustion and when the electron drops back down to a lower energy level, it gives off light with a specific energy of that transition, which corresponds to a particular color. We were amazed at the beauty of it all. The colors are created by burning metal salts, and the sound is created by the burning of fuel and air.The different colors and sounds are created by changing the chemical composition of the fuel and the metal salts, and the position of the stars in the shell.The fireworks finale was an incredible combination of light and sound, and it was amazing to fly a drone through it. Every time a KiwiCo crate shows up at our house, my kids get really excited. They know that inside is a hands-on project that they get to build with me. It’s a great way for them to learn about science, technology, engineering and design while playing and having fun. Plus, each crate comes with everything you need to complete the project, so there are no additional trips to the store.
KiwiCo has nine different product lines targeted at different age groups, from newborns up to 14+. We’ve been getting crates for three years now and I got to tour KiwiCo’s headquarters, so I saw how their crates are designed by experts and then tested with kids before they’re ever sent out. Plus, it’s a great value - most KiwiCo subscriptions work out to around $20 per month.
Working on these projects has become something that we do together and I really appreciate that. If you want to try it out, go to kiwico.com/veritasium to get your first month free. Using my link, you’re not only getting a great deal, you’re also helping to support this channel. And if you want to purchase single crates, that’s also an option through the KiwiCo store - they make great gifts!
I wanna thank KiwiCo for sponsoring this video and I wanna thank you for watching.