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TikTok’s favorite chemistry teacher wants you to be careful with hydrogen peroxide

Chemteacherphil is giving followers a second chance at science

Tessellated TikTok logos against a dark background. Illustration by Alex Castro / The Verge

High school chemistry teacher Phil Cook (@chemteacherphil) didn’t know anything about TikTok until one Friday in August, when a student in his class suggested that he make one of the day’s in-class demonstration: an experiment he calls the “gummy bear” sacrifice, where adding sugar (a gummy bear) to a test tube of potassium chlorate creates a contained explosion.

“I said, here’s my phone, make the video and we can take a look at it,” Cook says. He posted the video to TikTok and left school for the weekend. “I came back Monday, and the kids were like, ‘Did you see how many views you got?’ I hadn’t even looked at it,” Cook says. In just two days, the video had around 30,000 views.

After seeing the response, Cook decided to keep making videos of chemistry demonstrations. Now, he has over 900,000 followers on TikTok.

Rather than just show followers weird reactions taking place, he describes the science behind them — or asks viewers to guess what they think the science is. He’s done everything from oxidize iron to pull out the individual chemicals in a glow stick. “I see a lot of questions from people who are naturally curious,” he says. “I try to show them things that spark their curiosity.”

The following questions and answers have been lightly edited for clarity.

Tell me more about your first video — what were you trying to do with that experiment?

I teach an introductory chemistry course. I teach kids to make observations about matter and change, and being able to differentiate between physical and chemical change is the focus of the first lab activity. I ask them to cite evidence they see that supports that a chemical or physical change has occurred. The gummy bear sacrifice is a pretty popular demonstration, and there’s a lot of evidence the kids can grab onto. It’s pretty over the top, and emphasizes the concepts in the lab they’d just done.

How do you pick what experiments to put on TikTok?

There’s a common thread in where I am in the course and the demonstrations I do videos of. Sometimes I expand beyond that. Some things are just things I’m interested in, where I can throw a demo together and see what the chemical reaction is.

What’s behind the popularity of some of your videos?

I did one with a polymer sodium alginate, which is a polymer from seaweed. It’s used in molecular gastronomy. You can eat it. That video, when I walked through the process, inspired a lot of nostalgia.

Videos that have some sort of nostalgia — whether I mean to do it or not — that have references the kids pull out, are popular. With that particular video, everyone commented about Yu-Gi-Oh! I have no idea about Yu-Gi-Oh!, I guess it’s some card combination that results in something called polymerization.

Why is the “elephant toothpaste” reaction so popular on TikTok and other social media platforms?

It’s appealing because it’s accessible. Most anyone who is of a reasonable age can go and buy hydrogen peroxide. The catalyst [usually yeast] is relatively easy to acquire. I don’t think people really recognize how dangerous it is, especially when you’re using the concentrations of hydrogen peroxide that give the experiment a really rapid generation of oxygen gas. You need at least 30 percent hydrogen peroxide, which can be a huge hazard. If you look on YouTube you can see gallons of hydrogen peroxide dumped into a catalyst in a barrel — there’s a reason they’re wearing hazmat suits. Even then, it’s not necessarily safe. I would never do a demo on that order [of magnitude].

What are your goals for your chemistry videos?

Only reason I do them is because people seem to be interested in them. The comments I appreciate the most are the ones where people of whatever age say, “I wish my chemistry teacher would have done that, my experience was different, thanks for giving me a second shot at chemistry.” Those are why I do this.