How to make a Lava Lamp!
Clean 1litre plastic bottle
Alka Seltzer tablets
How Does it work To begin, the oil stays above the water because the oil is lighter than the water or, more specifically, less dense than water. Water molecules are attracted to other water molecules. They get along fine, and can loosely bond together (drops). Oil molecules are attracted to other oil molecules. But the structures of the two molecules do not allow them to bond together. When you added the tablet piece, it sank to the bottom and started dissolving and creating a gas. As the gas bubbles rose, they took some of the coloured water with them. When the blob of water reached the top, the gas escaped and down went the water.
By the way, you can store your lava lamp with the cap on and to bring it to life by adding another Alka-Seltzer!