LAVA

Recently my biology class did a lava lamp lab! We used a water bottle, vegetable oil, tap water, food coloring, and Alka Seltzer tablets. So, it wasn't an actual lava lamp...but it was pretty fun and easy to make! After doing our lab, we were asked to research the science behind a real lava lamp.

Interestingly enough, a real lava lamp isn't much different from the ones we made. The theory behind how a lava lamp (also known as a "liquid motion lamp") is that there are two liquids involved that are very close in density, and insoluable to one another. When you pour water and oil into a container, the water will sink below the oil due to the water having a higher density than the oil. Water and oil do not mix because an oil molecule is hydrophobic, or water fearing, so its molecules do not bond to the hydrogen molecules of the water.

When we added the food coloring, it only adhered to the water because the food coloring is hydrophilic, or water loving. The food coloring is able to bond to the water molecules, and thus the oil remains colorless. This is the same as in a real lava lamp. When you see the globs of "lava" bubbling and floating, you are really just seeing colored water ---sorry if you thought there was actual lava in lava lamps and I just spoiled your fun!

To actually make our "lava", we added Alka Seltzer tablets which chemically reacts when dropped into water because it contains citric acid and sodium bicarbonate, which produces the "fizz". This fizz was the energy source that moved our colored water to the top of the oil, and then the water sank back to the bottom of the water bottle, below the oil.  In a real lava lamp, the energy source is the heat from a light bulb. When the water becomes heated, it becomes less dense and floats to the top of the oil. As it cools down, it returns to its original location below the oil. This process continues, and gives the lava lamp it's unique characteristic.