Lava Mountain

This term in 5/6 SANE, modelled how to perform a mixture experiment for the Year 2 students. Michelle has provided the experiment for you to try at home:

To make a lava lamp you needed:

Materials:

• Oil
• Water
• Food Colouring
• A plastic bottle
• Funnel or measuring cup (optional)
• And most importantly alka seltzer. (Other fizzy tablets work, but not very well. You can also use salt, but Alka-Seltzer is the best.)

Method:

1. Pour water into the bottle up to about one-third.
2. Fill up the rest of the bottle with oil. Use a funnel or measuring cup so it doesn’t spill. You may need to wait a few minutes for the water and oil to separate.
3. Add drops of food colouring in. You will need to wait for the food colouring to pass through the oil and into the water.
4. Now break a tablet in half and drop it in. The tablet will dissolve and you will have (hopefully) a working lava lamp!

Please mind that unless you want a mouthful of oil and water (with a hint of Alka-Seltzer), do not drink the lava lamp. You can always add another piece of the tablet if the lava lamp starts to stop working.

What is happening?

The oil and water don’t mix, because the oil has a lower density (or is lighter) than the water. When you added the tablet piece, it sank to the bottom and started dissolving and creating a gas (carbon-dioxide). When 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 the water went back down.