Saturday Morning Science Experiment: Alka-seltzer lava lamp

Intermolecular polarity is a fancy way of saying "oil and water don't mix". Here, Science Bob explains why, and shows off a fun trick you can do over and over with oil, water, food coloring and alka-seltzer.

Thumbnail courtesy Flickr user ncfc0721, via CC

Previously:

Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.

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Joe

Actually he doesn’t explain why, he just repeats the term “intermolecular polarity”. What it means is that water molecules are polar; they have a positively charged side and a negatively charged side, and oil molecules are not. This means that water molecules are electrically attracted to other water molecules, but not so much to oil molecules, so the lowest-energy configuration is for all the water to be together.
Anonymous

Don’t screw the cap on the bottle after the alkasetzer is added. You might shoot your eye out or lose a finger.
lyd

Seems like he might have wanted to stress the idea that you probably shouldn’t cap the bottle until _after_ the alka-seltzer had completely dissolved.
t3hmadhatter

I did something quite similar as a kid. All started when I got interested in chemistry at about 5, and my parents said: “Don’t touch the 409 or the bleach, but everything else is fair game.” Stuck every sorta-chemical I could find in a plastic baggie and watched it bubble. Real cool.
Anonymous

Does Alka-seltzer change the oil chemically into non-food? If not, the oil could be re-used for baking after we get bored with the 60s. Natural food dyes might be recommended.

One could keep their lava lamp on the pantry shelf, ready to whip up an ever-popular “Lava Lamp Birthday Surprise Cake.”
Anonymous

Am I the only one a little irked that he referenced the different densities of oil and water to explain the lack of mixing? Ethanol, like oil, is less dense than water but it completely mixes. So density is not the answer of course but the intermolecular polarity referenced by the BoingBoinger.

ScienceBob, come on.
bmcraec

Surely this guy is somehow related to @hodgman! Not as witty, or as smart, from the example I see hereâ€¦ I hope I’m not finding seeing resemblance due to the haircut and glasses!
toolbag

When I was a kid we used to put water and alkaseltzer into plastic bottles and cap them. Then we’d shoot them with a .22 and howl and laugh when they exploded (yeah, I confess, I’m white trash). I don’t recall any of them exploding on their own though. They had plenty of time to pop too, I was/am a terrible shot.
Astragali

I like doing the fully-consumable version: using a few raisins in a glass of clear soda. Admittedly, it’s not as visually impressive as this version, but still fun to watch – and none of it goes to waste afterwards.
brianwilkinson

Interesting. Our Kidz Group will get a kick out of trying this experiment next week.

Brian
Anonymous

do Alka-seltzer have stocks for sale? I’m no expert in economic field but I’m sure they’ll benefit from this video.