Test tube lava lamps


The principle of "oil and water don't mix" is intensified by adding in alka seltzer bubbling and food coloring.



  • 1 tab of alka seltzer

  • 20 mL any oil

  • Food coloring (optional)

  • 250 mL water

Affiliate links to chemicals.

*Note: These chemicals can be purchased locally at stores such as Walmart/Target.

  • Glass dropper

  • Eye dropper

  • 4 Test tubes in stand

  • Nuffield spatula

  • Mortar and pestle


1. In mortar and pestle, crush alka seltzer.

2. Put 1 scoop of alka seltzer in each test tube. 

3. Put 1 drop of food coloring into each test tube.

4. Pour oil into test tube to half way mark (about 5 mL each).

5. Using the glass dropper, squirt water into each test tube.

6. Once the water hits the alka seltzer, the "lava lamp" begins.

The Science Behind the Reaction

Once the water reaches the alka seltzer, the two chemicals in the tablets can react (citric acid and bicarbonate) forming carbon dioxide.  The carbon dioxide is released as a gas, the bubbles you see floating through the oil to the top. 

Keep Experimenting!

Check out the Alka Seltzer website for more ideas on experimenting with alka seltzer.