By Super Awesome Sylvia and her dad, James

Today we’ll show you how to make your own groovy lava lamp, no heat required! All you need are a few things you just might have in your kitchen. Lets go!

For this groovy build, we’ll need:

  • Powdered sodium sicarbonate (baking soda) and powdered citric acid (from the canning section at the grocery store) or, some fizzy antacid tablets [more expensive, but easier to find])
  • Clean empty bottle (plastic or glass)
  • Water based food coloring
  • Vegetable oil (at least as much as your bottle holds)
  • Water
  • Funnel (optional, but really useful)

Subscribe to the MAKE Podcast in iTunes, download the m4v video directly, or watch it on YouTube and Vimeo.

First, take your bottle and fill it with about three centimeters of water (you don’t have to be exact). Then take your funnel and while tipping the bottle, carefully and slowly fill it with oil to just near the top (not too high though), making sure it doesn’t bubble too much. Don’t worry if it mixes a bit, it’ll separate eventually. Oil and water just don’t mix!

So, why don’t oil and water like to mix? Oil and water are made up of molecules, little groups of elements bonded together. Water molecules have one big oxygen atom, and two little hydrogen atoms. These give each side an opposite charge, making it a “polar” molecule. Polar molecules love to stick to other polar molecules. Oil is made up of carbon and cydrogen atoms formed into what are called hydrocarbon chains. The oil molecule’s charge is spread out, so it’s a “non-polar” molecule. Non-polar molecules like to stick to other non-polar molecules (but not as strongly as polar ones).

When a water molecule and a oil molecule come together, oil is what’s called, hydrophobic (it’s scared of water!). Because the oil is non-polar, it has no attraction to the water molecules, and they just don’t stick to each other. Water is also a lot more dense, so the oil sits on top of the water happily.

Back to the build, take your food coloring, and put about four to eight drops in. Watch as the drops fall through the oil as perfect little spheres. As soon as the drops hit the barrier between the oil and the water, they will either sit happily on the water’s surface tension for a bit, or they’ll pop and color the water immediately. If you’re using powdered ingredients, take equal parts of baking soda and citric acid, mix them together, then spoon them into the bottle. If you’re using antacid tablets, break them up a bit, then drop them in. Wow, Look at it go!

The sodium bicarbonate and citric acid only react in the water. As soon as they get there, they let off tons of little carbon dioxide bubbles that each grab their own bubble of colored water as they breach the oil/water barrier on the way up. These “double bubbles” fly up through the oil, then hit the surface, where the CO2 bubble pops, allowing the water drop to fall back down, and the whole cycle begins again. Amazing!

Remember: don’t put a cap on the bottle till the reaction is complete, otherwise pressure will build up and give you a nasty surprise when you open it later. Once it’s done, you can put the lid on and store it for as long as you want, and when you’re ready, just drop in some more fizzy stuff and enjoy the show! As an added bonus you can also put a light underneath, add some sparkles, or anything else that’s fun and buoyant.

That’s all we’ve got for this episode, remember to experiment with different colors and baking soda/citric acid mix ratios, show your friends, and get out there and MAKE something!

Check out more episodes of Sylvia’s Mini Maker Show.