What you need for this experiment
Fill bottle 3/4 of the way with vegetable oil.
Fill the bottle most of the rest of the way with water. (Don't overfill!)
Add 10 drops of food coloring.
Drop in 1/2 an Alka Seltzer tablet.
Enjoy lava lamp!
When bubbles stop try it again with an entire tablet.
Add a tablet any time you want to enjoy the lava lamp.
Why does it do that?
It is all about density! What is density you ask? The density of a material is determined by the amount of mass it contains per unit volume. Mathematically, it is calculated by dividing the mass by the volume. In our experiment, the water is more dense than the oil. That's why it sinks! When you drop the Alka Seltzer tablet into the water, the baking sodium and citric acid in the tablet react to form carbon dioxide. Our food colored water droplets hitch a ride on the carbon dioxide, which you see as the "lava" bubbles going up. Once they reach the top, the carbon dioxide escapes out into the air and the "lava" bubble falls back down. This reaction continues until the Alka Seltzer tablet is used up.
How To Make A Homemade Lava Lamp