Lava lamp science experiment

My sister had a lava lamp when we were kids. There’s something about the colors and the wax bubbles that is fascinating to watch! I’m not sure I want a real lava lamp in the boys’ room due to the potential disaster if it were to get knocked over, however we discovered a neat alternative a few months ago while conducting science experiments with friends.

To create your own lava lamp you’ll need:

- A clear glass bottle

- 3/4 cup of water

- vegetable Oil

- food coloring

- Alka Seltzer tablets

Pour the water into the bottle. We prefer glass over a plastic soda bottle because although you have to be more careful with the glass bottle, an accidental squeeze with the plastic bottle means a big, oily mess! Add 10 drops of food coloring to the bottle, and swirl to mix with the water. Using a funnel fill the bottle with vegetable oil; it should be almost full. And just like that, you’re ready for lava lamp action! Break an Alka Seltzer tablet in half and drop into the bottle – as soon as it hits the water it will start bubbling!

Here’s what’s happening:

Oil and water do not mix because water molecules cannot bond with oil molecules (intermolecular polarity). Also, water is denser than oil, and so it settles to the bottom. The tablet doesn’t react with oil, but when it sinks to the bottom it starts dissolving, creating gas bubbles. These bubbles are lighter than water and oil, and when they rise to the top they take some colored water with them. Upon reaching the surface the gas escapes, and the water then sinks back down through the oil.

For the lava lamp effect, shine a flashlight through the bottom of the bottle – super cool!

Remember to store your lava lamp with the cap on, but leave it off while there is still gas escaping. Waiting 10 minutes will allow the oil and water to completely separate out, and then you can start again with another tablet!