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One of the most popular projects from the new Geek Mom book is the DIY Lava Lamp. It's a super-simple chemistry project with a colorful twist.
We thought we'd give you another sneak peek into the book by sharing the directions to make your own DIY Lava Lamp. In keeping with the holidays, try making a bunch of them in red and green and setting them all off at once.
Here's how to make your own DIY Lava Lamp. For more background on the project, and to read about other activities – as well as our thoughts and advice about how to let your GeekMom light shine – pick up a copy of Geek Mom: Projects, Tips, and Adventures for Moms and Their 21st-Century Families by Natania Barron, Corrina Lawson, Jenny Williams and me!
And to see what they look like in action, here's a video of some of the Lava Lamps in action, from a summer science workshop led by one of our friends at Girls are Geeks!
Materials:
• Tall, thin recycled soda or water bottle (label removed), 16 oz (half-liter) size or larger
• Water
• Food coloring
• Baby oil, at least one 12 oz bottle
• Effervescent antacid tablets (such as Alka-Seltzer)
• LED stick-on push light
• Plastic plate to catch spills
Caution: oil may stain clothing, so wear a lab coat, apron, or old t-shirt
Step 1: Prepare the Bottom Layer of Colored Water
Fill the bottle about one-quarter of the way with water. Add five or six drops of liquid food coloring. (Take a few moments to watch as the dye begins to spread in vibrant tendrils of color—the result of Brownian motion, discovered by botanist Robert Brown in 1827.) The final color should be fairly dark.
Step 2: Add the Top Layer of Oil
Now it’s time to add the clear liquid. Baby oil is mostly mineral oil—a nontoxic by-product of the manufacture of gasoline—with a little fragrance added. You can also use any kind of cooking or skin care oil you have on hand, as long as it’s not too dark to see through. Pour the oil into the lava lamp bottle slowly, stopping when you reach the bottle’s shoulder. Leave a little head room so the lamp solution doesn’t bubble over. Let the bottle sit until the contents settle into two layers: colored water on the bottom, oil on top, with a nice sharp line in between.
Step 3: Turn on the Lights and Start the Action!
So far you’ve built what science teachers call a density column: one type of substance floating on another. To turn it into a lamp, just set the LED push light—a disk with three or four small bulbs embedded in it—on your plate and carefully place your lava lamp bottle on top so the liquid inside lights up. This homebrew lava lamp runs on chemical power instead of electric heat. To get it started, drop pieces of an effervescent (fizzing) antacid tablet like Alka-Seltzer into the bottle. Use as large a piece as possible—the bigger the piece, the more dramatic the effect!
As the tablet reaches the layer of water, it begins to release bubbles of carbon dioxide gas. Because gas is less dense than liquid, the bubbles float upward, carrying drops and blobs of water along with them. When the bubbles reach the surface, the gas keeps rising, but the water drops back down to the bottom of the lamp, creating the lava lamp effect. The lamp will keep running as long as the tablets are fizzing.
If your oil hasn’t gotten too cloudy, close up the bottle and save it for another day. But don’t put the cap on until all fizzing is over, or the pressure of the gas inside can create that explosion that your kids are waiting for!
