Make a Lava Lamp using materials found around your home. Then experiment with it.

Materials:

• Clear glass cup
• Water
• Vegetable oil
• Food dye
• Alka Seltzer
• Light – flashlight or lamp

Procedure:
Fill the glass ¼ full with water. Add some food dye. Fill the rest of the glass with vegetable oil (but not all the way to the top). Break up the Alka Seltzer tablet into 4 pieces. Drop 1 piece of Alka Seltzer into the glass and see what happens. Once it has worked, turn off the rest of the lights in the room and place the glass over a light. Drop in another piece of the Alka Seltzer and watch your lava lamp glow.

Questions to Ask Yourself:

• Why does this work?
• If I changed the order that I placed the materials in the glass, would it still work?
• If I changed ingredients, what would happen? (What’s the deal with water and oil–can I find other liquids that have the same relationship?)
• Why vegetable oil and not almond oil or olive oil? (What makes vegetable oil different?)
• Can I make this work for a longer period of time?

What’s Happening Here?
To start off, oil and water don’t mix. (why not?) So, combining them in a glass will give you separate layers. You want to add color to your water so you can see it—that’s why we used the food dye. And since you want the colorful bubbles to rise to the top, the water goes below the oil. Smart, right? Next is the bubbles—why do they rise through the oil? Density. The bubbles are made of water and gas. The gas gives the bubbles a lower density than the water and oil, so they rise up. Since the bubbles are made of water, they don’t mix with the oil, and they stay intact going through the oil. This gives a colorful effect so that we can light it up and turn it into a lava lamp.

For more information, go to this article from Scientific American, where I found out about this experiment. Don’t be disappointed that I am not a genius capable of coming up with this on my own. I am comfortable with my level of knowledge about science.