11 Chemical Reaction Videos, Explained
Each minute, a whopping 100 hours worth of videos are uploaded to YouTube—and a small, yet endlessly fascinating number of those are chemical reaction videos. To explain what exactly is happening in some of these videos we reached out to an expert at the American Chemical Society, John M. Malin, Ph.D, to let us in on some of these awesome chemistry secrets.
1. Ignited ammonium dichromate
No, this chemical reaction isn't "opening a portal to hell," as you may have seen it described on Facebook or other social media sites. A compound known as ammonium dichromate (which was actually used in the early days of photography to capture images) is ignited with a lighter, which reacts by forming a greenish/black powder and producing nitrogen gas. “The exothermic reaction (aka, any chemical reaction that produces heat, light, or sound) produces heat and sparks until the dichromate is used up,” Dr. Malin says. But that’s not all: As a little surprise at the bottom, “demonstrators have evidently placed some mercuric thiocyanate which also reacts when ignited to form the snake-like tendrils shown coming up through the ‘volcano.’” We’ll see this again below. Also, bonus points for the unseen kids yelling “Kraken!”
2. Pharoah’s Serpent
This reaction, called “Pharoah’s Serpent,” is created by burning bits of mercuric thiocyanate, the same compound that produced the Kraken-like tendrils in the experiment above. The tendrils are a byproduct of the ignition, and are made from a resulting compound called carbon nitride. But be warned: If you get your hands on mercuric thiocyanate, don't burn it just anywhere; the demonstrations here and above include highly toxic materials and the reactions they produce are extremely poisonous. These experiments “should only be done in a fume hood,” Dr. Malin says.
3. Elephant’s Toothpaste
Do all chemical reactions have funny names? In this one, known as the “Elephant’s Toothpaste,” hydrogen peroxide rapidly decomposes and produces a foam substance. First, the hydrogen peroxide is mixed with liquid soap or dishwashing detergent, then an iodide salt is added to catalyze and decompose the hydrogen peroxide very quickly, creating a large amount of oxygen and water. The soap causes the oxygen and water to bubble, which makes the foam. To spiff up the experiment, food coloring was added above to give the foam an orange tinge.
4. Iodine Clock
This video gives you the steps and the items you need to do make the “Iodine Clock” reaction, but here's what's happening on a molecular level: A sulfite ion compound (which loses an electron) reacts to an iodate ion (which accepts the lost electron), creating the important-sounding triiodide ion (fancy-talk for an ion with three iodine atoms). Starch is added, which gets rid of the sulfite and produces the dark purple color. Adding sulfite back then makes the purplish iodine turn back into compound iodide, making the color go away.
5. Coke and Milk
You take some Coke, you take some milk, you wait six hours and what do you get? A weird orangey mush! “Milk contains the protein casein which, upon acidification, slides out of the solution to form a viscous, gooey substance,” Dr. Malin says. When you let the Coke-Milk mixture sit for six hours, the casein sinks to the bottom of the bottle, absorbing most of the brown coloring in the Coca-Cola and making the remaining liquid the amber color seen in the video.
6. Black Snake
Concentrated sulfuric acid is a pretty effective dehydrating agent. If you add it directly to normal table sugar, Dr. Malin says, “it rips the water molecules right out of the carbohydrate,” leaving only carbon left. The reaction makes the carbon expand, which produces the weird-looking black substance seen above.
7. Purple Smoke
This experiment is good if you need to make some kind of ninja smoke-screen escape—but you’ll probably need a lot of powdered iodine to do it. This one works very similar to the reaction seen in #4: the powdered iodine is an oxidant (it accepts electrons in a reaction), while powdered metallic zinc is a reductant (it loses an electron in a reaction). By adding a drop of water to both, it helps initiate contact between the two, which produces the chemical compound zinc iodide. The quick reaction produces a lot of heat, and the heat vaporizes the iodine in the compound, which produces the purple vapor.
8. Hydrogen Peroxide + Blood
Any squeamish readers out there, look away now, and any chemistry nerds out there take notice! In this video, a kooky Russian chemist who calls himself the “Crazy Russian Hacker” drops pig blood into hydrogen peroxide with some bubbly results. The blood is acting as a catalyst for the breakdown of the hydrogen peroxide, essentially speeding up the process due to the iron in the blood’s hemoglobin (a protein that transports oxygen in the blood). According to Dr. Malin, “The reaction produces oxygen molecules and water,” and “the foam is due to oxygen bubbles forming in the blood/water emulsion.”
9. Superabsorbent Polymer
“Super absorbent polymers (SAPs) can absorb as much as 300 times their weight in water,” Dr. Malin says. In this case, the SAP is sodium polyacrylate, a substance used by plumbers to unclog toilets that can also be used in disposable diapers. Add some food coloring to water and then throw in an SAP and the result is a pseudo-solid with a squishy texture.
10. Fake Snow
If you’re stuck in a tropical climate and need a DIY way to create some powder, the super absorbent polymer from the previous post might be your best bet. Make sure to add more sodium polyacrylate to water, which makes it more powdery, and this time you don’t have to include any food coloring. The only drawback is that this “snow” is room temperature.
11. Non-Newtonian Fluid
This one is my personal favorite. According to Dr. Malin, “mixing corn starch and water forms a non-Newtonian fluid, i.e., a fluid that becomes more viscous (gets stiffer) when it is agitated.” The video above shows that agitation in the form of different sound frequencies played through a speaker cone, which forces the non-Newtonian fluid (which are named after Isaac himself because of how they seem to violate his laws) to stiffen and localize in certain places, thus making it stand up depending on where the sound waves were the strongest.