Branch of Science: Chemistry
Concept: Oil and Water Immiscibility

LAVA LAMP

A lava lamp gives off a one-of-a-kind glow. Its dancing blobs bring hours of enjoyment. Make your own with this project. Then pride yourself on knowing the science behind it.

You’ll Need:

• Clean soda or water bottle (any size)
• Water
• Vegetable oil
• Food coloring (any color)
• Effervescent tablets (Alka-Seltzer)
• Battery-operated tea light

Put It Together:

1. Fill the bottle about 1/4 full of water.
2. Pour vegetable oil into the bottle until it is nearly full.
3. Add 6 to 10 drops of food coloring into the bottle. Shake the bottle if needed to dissolve the food coloring.
4. Wait until the water and oil have separated. Place 1/4 of an effervescent tablet into the bottle. Watch the show!

   

5. When the bubbles stop, place another 1/4 tablet into the bottle. This time place the lit tea light upside down in the top of the bottle.
6. Take the lamp into a dark room for a lava lamp experience.
7. Add more tablets, 1/4 at a time, to keep the fun going.

Reusable Knowledge

The oil and water don’t mix together. Why? Water is much denser than oil. Its molecules are more tightly packed together than oil’s are. This makes water sink. The structure of the molecules is different for oil and water too. Water’s molecules are polar, meaning they have a negative charge on one end and a positive charge on the other. Their charges hold the molecules to each other. Oil is nonpolar, without a charge, and doesn’t mingle with the water molecules. The fizzing tablet releases gas. As the gas rises to the surface, it pulls colored water with it. After the gas escapes, the water blobs sink back to the bottom of the bottle.