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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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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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Medicine
New Cancer-Fighting Nanobots Can Track Down Tumors and Cut Off Their Blood Supply
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iStock

Scientists have developed a new way to cut off the blood flow to cancerous tumors, causing them to eventually shrivel up and die. As Business Insider reports, the new treatment uses a design inspired by origami to infiltrate crucial blood vessels while leaving the rest of the body unharmed.

A team of molecular chemists from Arizona State University and the Chinese Academy of Sciences describe their method in the journal Nature Biotechnology. First, they constructed robots that are 1000 times smaller than a human hair from strands of DNA. These tiny devices contain enzymes called thrombin that encourage blood clotting, and they're rolled up tightly enough to keep the substance contained.

Next, researchers injected the robots into the bloodstreams of mice and small pigs sick with different types of cancer. The DNA sought the tumor in the body while leaving healthy cells alone. The robot knew when it reached the tumor and responded by unfurling and releasing the thrombin into the blood vessel that fed it. A clot started to form, eventually blocking off the tumor's blood supply and causing the cancerous tissues to die.

The treatment has been tested on dozen of animals with breast, lung, skin, and ovarian cancers. In mice, the average life expectancy doubled, and in three of the skin cancer cases tumors regressed completely.

Researchers are optimistic about the therapy's effectiveness on cancers throughout the body. There's not much variation between the blood vessels that supply tumors, whether they're in an ovary in or a prostate. So if triggering a blood clot causes one type of tumor to waste away, the same method holds promise for other cancers.

But before the scientists think too far ahead, they'll need to test the treatments on human patients. Nanobots have been an appealing cancer-fighting option to researchers for years. If effective, the machines can target cancer at the microscopic level without causing harm to healthy cells. But if something goes wrong, the bots could end up attacking the wrong tissue and leave the patient worse off. Study co-author Hao Yan believes this latest method may be the one that gets it right. He said in a statement, "I think we are much closer to real, practical medical applications of the technology."

[h/t Business Insider]

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