Lava Lamp Density

You can make your own lava lamp to watch as carbon dioxide gas is released, creating a cool and colorful science show.  We’ll talk about density as we go along with the experiment.

You’ll need:

  • water
  • a clear bottle or jar (we used a pretty wide jar, but narrow ones work even better as the bubbles are more visible against the outside walls)
  • vegetable oil
  • food coloring
  • Alka-seltzer tablets


And here’s what you do:

Start by filling the bottle or jar about 1/4 full of water.  Add 12-15 drops of food coloring to it.


Then fill the rest of of it up with vegetable oil.  Give the oil and water a few minutes to separate.  You’ll be able to see the two distinct layers, and because the water is more dense than the oil it sinks to the bottom.


Drop Alka-Seltzer tablets in.


If you want, you can cut an Alka-seltzer tablet into 6 pieces and drop the pieces into the bottle one at a time to create even more bubbles.  You’ll be able to see the carbon dioxide bubbling like crazy, creating a cool show.


When it stops just go ahead and put another piece of the tablet in.


The carbon dioxide gas bubbles, less dense than either the water or the oil, rise up through the bottle, with little colored water droplets in tow.  The gas escapes when it reaches the surface, and then the denser water droplets fall back down again, without the gas to cling to any longer.


And there you have it – lava lamp density!


More From Layers of Learning

For another cool density experiment, check out the floating eggs experiment:

Floating eggs experiment

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