Featured Projects: DIY Bubbling “Lava” Lamp

    Water and oil don’t mix. But if you add something fizzy to make bubbles, you’ll get a very interesting result.

    Materials:
    • Clear bottle (a plastic water or pop bottle will do)
    • Vegetable oil
    • Water
    • Food coloring
    • ‘Fizzy’ tablets, like antacid or denture cleaner – make sure the label says “effervescent”, which means something that gives off bubbles or is fizzy.

    Tip – you can get all of these items in a dollar store, if you don’t already have them at home.

    Steps:

    1. Fill the bottle about ¼ of the way with water.

    2. Pour in vegetable oil, leaving about 2 inches of space at the top.
    What’s happening here? See how the oil floats on top of the water? Oil molecules and water molecules are different; they aren’t attracted to each other, so they don’t mix together. Also, oil molecules are lighter than water molecules – so they float on top.

    3. Pour in a few drops of food coloring
    Food coloring is water based, so it’s attracted to the water, but repelled by the oil. Watch it drop straight through the oil into the water, and mix with the water. Put in enough food coloring to get a good dark color.

    4. Once you have your water base colored, you can add in a fizzy tablet. If it’s too large to fit in your bottle’s opening, go ahead and break it up. Watch what happens once the tablet sinks down through the oil and mixes with the water.

    What’s happening here?  When the tablet meets the water, bubbles of carbon dioxide are released. The carbon dioxide binds with the water, carrying it upward, because with that gas attached, it’s now lighter than the oil. Once it breaks the surface, the bubbles pop, the carbon dioxide is released, and the water once again becomes heavier than the oil, causing it to sink back down. So-called Lava lamps work on the same principle.

    Hot wax rises to the top, cools, becomes heavier, and sinks back down. (If you haven’t seen a lava lamp, google it!)

    5. Bonus: Unexpected Results!
    When I bought the materials for this experiment, the store didn’t have antacid, so I substituted denture cleaner. Now, I know its job is to remove stains – meaning colors – from dentures, but I didn’t know how good it is at its job. When I looked at my bottle the next morning…

    Every trace of that very dark blue was gone!

    6. Bonus #2 – Wave bottle
    Once you run out of fizzy tablets, your bottle turned on its side becomes a cool looking wave bottle. It looks much better with color, so add in some more food coloring if yours has been cleaned away!