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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.

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The American Museum of Natural History
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10 Surprising Ways Senses Shape Perception
The American Museum of Natural History
The American Museum of Natural History

Every bit of information we know about the world we gathered with one of our five senses. But even with perfect pitch or 20/20 vision, our perceptions don’t always reflect an accurate picture of our surroundings. Our brain is constantly filling in gaps and taking shortcuts, which can result in some pretty wild illusions.

That’s the subject of “Our Senses: An Immersive Experience,” a new exhibition at the American Museum of Natural History in New York City. Mental Floss recently took a tour of the sensory funhouse to learn more about how the brain and the senses interact.

1. LIGHTING REVEALS HIDDEN IMAGES.

Woman and child looking at pictures on a wall

Under normal lighting, the walls of the first room of “Our Senses” look like abstract art. But when the lights change color, hidden illustrations are revealed. The three lights—blue, red, and green—used in the room activate the three cone cells in our eyes, and each color highlights a different set of animal illustrations, giving the viewers the impression of switching between three separate rooms while standing still.

2. CERTAIN SOUNDS TAKE PRIORITY ...

We can “hear” many different sounds at once, but we can only listen to a couple at a time. The AMNH exhibit demonstrates this with an audio collage of competing recordings. Our ears automatically pick out noises we’re conditioned to react to, like an ambulance siren or a baby’s cry. Other sounds, like individual voices and musical instruments, require more effort to detect.

3. ... AS DO CERTAIN IMAGES.

When looking at a painting, most people’s eyes are drawn to the same spots. The first things we look for in an image are human faces. So after staring at an artwork for five seconds, you may be able to say how many people are in it and what they look like, but would likely come up short when asked to list the inanimate object in the scene.

4. PAST IMAGES AFFECT PRESENT PERCEPTION.

Our senses often are more suggestible than we would like. Check out the video above. After seeing the first sequence of animal drawings, do you see a rat or a man’s face in the last image? The answer is likely a rat. Now watch the next round—after being shown pictures of faces, you might see a man’s face instead even though the final image hasn’t changed.

5. COLOR INFLUENCES TASTE ...

Every cooking show you’ve watched is right—presentation really is important. One look at something can dictate your expectations for how it should taste. Researchers have found that we perceive red food and drinks to taste sweeter and green food and drinks to taste less sweet regardless of chemical composition. Even the color of the cup we drink from can influence our perception of taste.

6. ... AND SO DOES SOUND

Sight isn’t the only sense that plays a part in how we taste. According to one study, listening to crunching noises while snacking on chips makes them taste fresher. Remember that trick before tossing out a bag of stale junk food.

7. BEING HYPER-FOCUSED HAS DRAWBACKS.

Have you ever been so focused on something that the world around you seemed to disappear? If you can’t recall the feeling, watch the video above. The instructions say to keep track of every time a ball is passed. If you’re totally absorbed, you may not notice anything peculiar, but watch it a second time without paying attention to anything in particular and you’ll see a person in a gorilla suit walk into the middle of the screen. The phenomenon that allows us to tune out big details like this is called selective attention. If you devote all your mental energy to one task, your brain puts up blinders that block out irrelevant information without you realizing it.

8. THINGS GET WEIRD WHEN SENSES CONTRADICT EACH OTHER.

Girl standing in optical illusion room.

The most mind-bending room in the "Our Senses" exhibit is practically empty. The illusion comes from the black grid pattern painted onto the white wall in such a way that straight planes appear to curve. The shapes tell our eyes we’re walking on uneven ground while our inner ear tells us the floor is stable. It’s like getting seasick in reverse: This conflicting sensory information can make us feel dizzy and even nauseous.

9. WE SEE SHADOWS THAT AREN’T THERE.

If our brains didn’t know how to adjust for lighting, we’d see every shadow as part of the object it falls on. But we can recognize that the half of a street that’s covered in shade isn’t actually darker in color than the half that sits in the sun. It’s a pretty useful adaptation—except when it’s hijacked for optical illusions. Look at the image above: The squares marked A and B are actually the same shade of gray. Because the pillar appears to cast a shadow over square B, our brain assumes it’s really lighter in color than what we’re shown.

10. WE SEE FACES EVERYWHERE.

The human brain is really good at recognizing human faces—so good it can make us see things that aren’t there. This is apparent in the Einstein hollow head illusion. When looking at the mold of Albert Einstein’s face straight on, the features appear to pop out rather than sink in. Our brain knows we’re looking at something similar to a human face, and it knows what human faces are shaped like, so it automatically corrects the image that it’s given.

All images courtesy of the American Museum of Natural History unless otherwise noted.

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NASA/JPL-Caltech
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Space
More Details Emerge About 'Oumuamua, Earth's First-Recorded Interstellar Visitor
 NASA/JPL-Caltech
NASA/JPL-Caltech

In October, scientists using the University of Hawaii's Pan-STARRS 1 telescope sighted something extraordinary: Earth's first confirmed interstellar visitor. Originally called A/2017 U1, the once-mysterious object has a new name—'Oumuamua, according to Scientific American—and researchers continue to learn more about its physical properties. Now, a team from the University of Hawaii's Institute of Astronomy has published a detailed report of what they know so far in Nature.

Fittingly, "'Oumuamua" is Hawaiian for "a messenger from afar arriving first." 'Oumuamua's astronomical designation is 1I/2017 U1. The "I" in 1I/2017 stands for "interstellar." Until now, objects similar to 'Oumuamua were always given "C" and "A" names, which stand for either comet or asteroid. New observations have researchers concluding that 'Oumuamua is unusual for more than its far-flung origins.

It's a cigar-shaped object 10 times longer than it is wide, stretching to a half-mile long. It's also reddish in color, and is similar in some ways to some asteroids in our solar system, the BBC reports. But it's much faster, zipping through our system, and has a totally different orbit from any of those objects.

After initial indecision about whether the object was a comet or an asteroid, the researchers now believe it's an asteroid. Long ago, it might have hurtled from an unknown star system into our own.

'Oumuamua may provide astronomers with new insights into how stars and planets form. The 750,000 asteroids we know of are leftovers from the formation of our solar system, trapped by the Sun's gravity. But what if, billions of years ago, other objects escaped? 'Oumuamua shows us that it's possible; perhaps there are bits and pieces from the early years of our solar system currently visiting other stars.

The researchers say it's surprising that 'Oumuamua is an asteroid instead of a comet, given that in the Oort Cloud—an icy bubble of debris thought to surround our solar system—comets are predicted to outnumber asteroids 200 to 1 and perhaps even as high as 10,000 to 1. If our own solar system is any indication, it's more likely that a comet would take off before an asteroid would.

So where did 'Oumuamua come from? That's still unknown. It's possible it could've been bumped into our realm by a close encounter with a planet—either a smaller, nearby one, or a larger, farther one. If that's the case, the planet remains to be discovered. They believe it's more likely that 'Oumuamua was ejected from a young stellar system, location unknown. And yet, they write, "the possibility that 'Oumuamua has been orbiting the galaxy for billions of years cannot be ruled out."

As for where it's headed, The Atlantic's Marina Koren notes, "It will pass the orbit of Jupiter next May, then Neptune in 2022, and Pluto in 2024. By 2025, it will coast beyond the outer edge of the Kuiper Belt, a field of icy and rocky objects."

Last month, University of Wisconsin–Madison astronomer Ralf Kotulla and scientists from UCLA and the National Optical Astronomy Observatory (NOAO) used the WIYN Telescope on Kitt Peak, Arizona, to take some of the first pictures of 'Oumuamua. You can check them out below.

Images of an interloper from beyond the solar system — an asteroid or a comet — were captured on Oct. 27 by the 3.5-meter WIYN Telescope on Kitt Peak, Ariz.
Images of 'Oumuamua—an asteroid or a comet—were captured on October 27.
WIYN OBSERVATORY/RALF KOTULLA

U1 spotted whizzing through the Solar System in images taken with the WIYN telescope. The faint streaks are background stars. The green circles highlight the position of U1 in each image. In these images U1 is about 10 million times fainter than the faint
The green circles highlight the position of U1 in each image against faint streaks of background stars. In these images, U1 is about 10 million times fainter than the faintest visible stars.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Color image of U1, compiled from observations taken through filters centered at 4750A, 6250A, and 7500A.
Color image of U1.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Editor's note: This story has been updated.

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