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20 Minute Labs: Lava Lamp in a Glass

20 minute labs lava logo | Yellow Scope blog



lava lamps | Yellow Scope blogHave you ever seen a lava lamp? They're basically an ongoing chemical reaction in a bottle! They were a big hit in the past, and people would buy them to add some fun light and a mesmerizing visual to their room. 

In this month's 20 Minute Lab, we'll use some household items to make our own lava lamps!

This experiment is great because it's fun day or night (with a little flashlight help), and you can use the 'lamp' over and over again!

Note: make sure NOT to drink or taste your lava lamp - it's would taste gross and wouldn't be good for your body!


  • lava lamp supplies | Yellow Scope blogSeveral tablets of Alka-Seltzer (generic brands are fine)
  • vegetable oil (about 2+ cups)
  • food coloring
  • drinking glass
  • measuring cup
  • water


  • tray (to catch spills)
  • flashlight | Yellow Scope bloglarge flashlight (for nighttime fun!)
  • chopstick (for experimenting with stirring)
  • extras of everything to make more than one lava lamp!


  1. lava lamp steps | Yellow Scop blogFirst, fill your measuring cup with 1/2 cup of water.
  2. Add about 20 drops of food coloring and stir. (Remember, you can mix colors by adding 10 drops of different colors or some other combination!)
  3. Fill your glass a bit over halfway up with oil.
  4. Add the colored water to your glass (watch it sink and separate!)
  5. Break one Alka-Seltzer tablet into three or four pieces.
  6. Drop one of the pieces into your glass and watch what happens!


  1. flashlight | Yellow Scope blogAt night (or in a dark room), place the glass on top of a wide flashlight that will stand on its own. (Or you can make your own creative setup - we cut a small hole out of cardboard, then placed the glass on top and a bike light underneath).
  2. Turn the lights off, then add your Alka-Seltzer tablet and watch the lit up effect!

 (Notice how you can just keep adding pieces of tablet to keep the lamp going!)


What's going on?

lava lamp pour | Yellow Scope blogBefore you put your tablet in the mix, you poured the colored water into the oil. Did you notice how the water went straight to the bottom?


That happened because water molecules are smaller than oil molecules, so they can pack more tightly together. This means that water is denser than oil.

It's sort of like the difference between sand and marbles - sand (like water) is made up of tiny bits, and marbles (like oil) are made of big bits. And you know that you can pack more sand into an area than marbles!

oil water molecules | Yellow Scope blogWater and Oil Don't Mix

Water doesn't mix with oil because oil is made of 'hydrophobic', or water-fearing, molecules that want to keep away from water. The food coloring, on the other hand, mixes well with water and dissolves into it (notice how the oil stays the same color).

fizz | Yellow Scope BlogChemical Reaction

Alka-Seltzer has sodium bicarbonate and citric acid in it. When you put the tablet in water, a chemical reaction occurs: the sodium bicarbonate and citric acid molecules bump into each other, swap parts, and form new molecules. One of those new molecules is carbon dioxide. 

The fizzing action is actually bubbles of carbon dioxide gas. The bubbles  rise to the top of the glass, and as they do, they attach to globules of colored water and bring them up to the top as well!

Once they reach the top, the bubbles burst, leaving nothing to keep the dense blobs of water from sinking again.

Keep experimenting!

Try these variations to keep the fun going:
  • alka-seltzer tablet | Yellow Scope blogTry different sizes of the tablet - what happens with a whole tablet? What about with lots of small pieces at once?
  • What happens if you use more water in the glass than oil?






    Let us know what you did. Share your photos and results with us on Facebook, Twitter, Instagram, or send us an email to We love getting your messages!

    For more exciting experiments, check out our Yellow Scope Science Kits on the Shop tab of our website!


    Chelsea Schuyler
    Chelsea Schuyler