Lava Lamp

Make your own hypnotic lava lamp with oil and water and a secret ingredient that makes it fizz and bubble.

Suitable for kids aged 5+ with parental supervision.

CAUTION
Remember Alka-Seltzer tablets are a medicine, do not ingest. Read the packet instructions for more information.

You Need:
  • An empty soft drink bottle with cap, or clear jar/container with a lid
  • Vegetable oil
  • Alka-Seltzer tablets (from the supermarket)
  • Food colouring
  • Water
What to do:
  1. Fill the bottle (or container) about full with vegetable oil.
  2. Carefully fill the rest of the bottle/container with water (nearly to the top but not overflowing). Why doesnt the water mix with the oil layer?
  3. Add about 10-15 drops of food colouring so the water is a nice deep vibrant colour. Why does the dye only colour the water?
  4. Break an Alka-Seltzer tablet into 6-8 pieces.
  5. Drop one of the Alka-Seltzer pieces into the bottle/container. What happens? When the fizzing stops add another piece. Then another its just like a lava lamp! Cool man!
  6. When you have finished with the Alka-Seltzer tablets and the bubbling has stopped, put the lid on the bottle/container and tip it back and forth. Watch the wave and blobs develop and combine. Shake the bottle/container. What happens? Does the water and oil stay mixed?

Why is it so?

Oil and water dont mix the water molecules (highly charged hydrophilic compounds) do not like the oil molecules (hydrophobic long chains of carbon). Even when shaken, the oil breaks into smaller droplets so it might appear mixed, but isnt. When left undisturbed, the oil and water will eventually separate into distinct layers. Food dye only mixes with the water.

Water is heavier (more dense) than oil, so when the water is added to the bottle/container it sinks to the bottom.

The Alka-Seltzer tablets react with the water to make bubbles of carbon dioxide gas. These gas bubbles attach themselves to the blobs of coloured water taking them to the surface through the oil. When the bubbles pop at the surface, the blob of coloured water sinks back down to the bottom. Definitely a groovy lava lamp!