Materials

  • Clear plastic bottle with top

  • Vegetable Oil

  • Water

  • Food coloring – primary colors or neon

  • Original Alka Seltzer tablets

Alka-Seltzer

Lava Lamp

Instructions

Prepare Bottle:

  • Fill the bottle 1/2 full with vegetable oil.

  • Fill the rest of the bottle with water.

  • Add about 10 drops of food coloring.

Prepare Alka-Seltzer:

  • Divide the Alka-Seltzer tablet into 8 pieces.

Assembly and Reaction:

  • Drop one of the tiny pieces of Alka-Seltzer into the oil and water mixture.

Observation:

  • When the bubbling stops, add another piece of Alka-Seltzer. It’s just like a lava lamp!

Questions:

  • What do you think would happen with the liquids at different temperatures?

  • What do you think would happen if you make a lava lamp with different proportions of water and oil, such as ¾ oil or ¼ oil?

  • What other water soluble substances could be used in place of the food coloring? We highly recommend trying water color paints or different juices (hint: try cabbage juice!).

What is happening?

When Alka-Seltzer reacts with water, it produces carbon dioxide gas, creating a lava lamp effect as bubbles rise through oil carrying colored water until they burst at the top of the jar.