Embrace your inner 1970’s teenage self with this makeshift lava lamp — no heat required.
What You Need
- Corn oil
- A plastic bottle
- Food coloring
- Alka-Seltzer tablets
What to Do
1. Fill 1/4th of a clear plastic bottle with water.
2. Add a few drops of food coloring of your choice.
3. Tilt the bottle to the side and slowly pour in corn oil.
4. Set the bottle back upright.
5. Let the oil and water settle and add two Alka-Seltzer tablets.
What's Going On?
Initially, the water has a higher density than the oil; in other words, the mass of a certain volume of water is greater than oil of the same volume. As a consequence, the water sinks to the bottom of the bottle and the oil sits on top of it without mixing. Food coloring allows you to view this separation more easily.
When you drop the Alka-Seltzer tablets in the bottle, they’ll sink to the bottom and begin to dissolve in the water. This reaction will generate carbon dioxide bubbles that float to the top and escape through the open lid. Colored water droplets will latch onto these bubbles and rise to the top of the bottle. At the top, the carbon dioxide gas will escape and the water will sink back down toward the bottom.
While traditional lava lamps require liquids of different densities, their densities are much closer. The two liquids must also be insoluble, meaning they do not mix. Upon turning on the lava lamp’s light, the liquid at the bottom of the container, which is denser, will heat and expand.
As the liquid expands, the volume of the liquid increases, and its density decreases. This causes the liquid to rise and cool. As the liquid cools, the volume decreases; density increases; and it sinks back down the bottom of the container where it will be reheated — continuing the movement indefinitely.