Experiment Details

• Grade Level: 3rd–6th Grade (adaptable for K–8)
• Key Topics: Density, Chemical Reactions, Immiscible Liquids
• Estimated Time: 20–25 minutes
• Mess Factor: Low to medium (use a tray or towel under bottles!)

Purpose: To show how oil and water behave when mixed, and how adding a fizzy tablet (effervescent) creates moving bubbles—mimicking a real lava lamp!

Hypothesis: If I put an effervescent tablet into a bottle filled with oil and colored water, then bubbles will form and move up and down like a lava lamp because gas is created and moves through the liquids.

Step-by-Step Instructions (with Pictures)

1. 1. Fill your bottle about one-quarter full with water.
2. 2. Add 5–6 drops of food coloring to the water and swirl gently to mix.
3. 3. Using a funnel, pour vegetable oil into the bottle until it is nearly full, leaving some space at the top.
4. 4. Wait a few minutes for the oil and colored water to separate into two layers (oil on top, water on bottom).
5. 5. Break your effervescent tablet into 2–3 pieces.
6. 6. Drop one piece of the tablet into the bottle and watch as bubbles begin to form and move up and down through the oil!
7. 7. When the bubbling slows, add another tablet piece to keep the lava lamp effect going.
8. 8. Clean up any spills with your towel or cloth.

Results & Scientific Explanation

When you add the effervescent tablet, it reacts with the water to produce carbon dioxide gas. These gas bubbles attach to drops of colored water, making them lighter so they rise through the oil. At the top, the bubbles pop and the colored water droplets sink again—just like the wax in a real lava lamp! Oil floats above water because it’s less dense and the two liquids don’t mix (they’re “immiscible”). This experiment is a visual and memorable way to teach students about density, chemical reactions, and why some liquids don’t mix.

• Oil and water separate: Oil is less dense and sits on top of water.
• Bubbles form: Effervescent tablet creates carbon dioxide gas bubbles.
• Lava lamp effect: Gas bubbles carry colored water up through oil; when gas escapes, the water sinks again.

Real-World Connection: How Do Real Lava Lamps Work?

Real lava lamps use wax and colored liquid. When heated, the wax becomes less dense and rises, then cools and sinks—creating mesmerizing motion. Your science bottle uses gas bubbles and density to mimic the effect!