Homemade Lava Lamp

Understand how liquids of different densities interact and how gas can move liquids by creating a bubbling lava lamp effect.

What you need

• A clear bottle or glass jar
• Vegetable oil
• Water
• Food coloring
• 1 effervescent tablet (like Eno or Alka-Seltzer)

How it works

Water is denser than oil, so it sinks. The tablet reacts with the water and produces gas bubbles (CO₂) that rise through the oil, carrying colored water up. When the bubbles pop, the colored drops fall again. This creates a bubbling lava lamp effect and demonstrates density and chemical reaction.