Let’s get groovy and bring some lava to life– the kind that doesn’t melt your hand off. You should still ask an adult to help you with this one.
What you need:
- A glass container. A bottle, beaker, cup… anything you can see through that holds liquid.
- Food coloring
- Mineral oil or vegetable oil
Fill 25% of your bottle with water. You can eye-ball this amount. Just aim for 1/4th of the bottle to be water. Then take your food coloring and add about 4 drops to the water. Next, add your oil and fill to the top of the glass. Then take a small piece of Alka seltzer and drop it in.
BOOM! Just kidding, there should be NO explosions.
What do you see? Lots of colorful bubbles rising up through your glass and falling back down?
Lava lamps use the heat from their light to activate the blobs. We use Alka-Seltzer instead. Because water is more dense than oil, it will sink to the bottom when the two are put in the same container.
The Alka-Seltzer reacts with the water to produce carbon dioxide (CO2) gas bubbles. These stick to the water droplets. The water/gas combo is less dense than the oil, so they rise to the top of the bottle. The gas bubbles pop at the top and escape into the air. This allows the dense water to sink back to the bottom again.