Lava Lamp

Make your own homemade lava lamp. You can make it in a bottle, with a lid if you want to keep it, or just use a tall glass.

What you need:

• clear bottle or tall glass
• vegetable oil
• water
• food dye
• Alka-Seltzer tablet (found in the medicine aisle in the supermarket)

What to do:

1. In a container, add a few drops of food dye to some water.
2. Fill the bottle or glass about 3/4 with vegetable oil.
3. Pour the coloured water into the vegetable oil to fill the bottle/glass. Wait for the two layers to separate.
4. Break up an Alka-Seltzer tablet into little pieces.
5. Drop a few small pieces of Alka-Seltzer tablet into the jar/glass.
6. Watch what happens.
7. When the reaction stops, you can add more pieces of Alka-Seltzer tablets to start it all over again.
8. If your mixture is in a bottle, you can put a lid on and keep it.

What happens:

Oil is less dense than water, so the liquids form two separate layers, with the oil on top. When you add the Alka-Seltzer tablet, it sinks into the water layer which causes a chemical reaction where carbon dioxide (CO₂) is made. The carbon dioxide sticks to the water droplets, which makes them less dense and causes them to rise. You can easily see the water because it is coloured with food dye. Once the water droplets get to the top of the oil, the carbon dioxide bubbles pop, causing the water to sink back down again.