This week is Science Week, so we decided to make a lava lamp!

We used pure vegetable oil , red food colouring, water and Alka-Seltzer tablets. First, we put in a little bit of water into a big 2 litre bottle then filled the rest of it up with vegetable oil, almost to the top. The water and vegetable oil don’t mix so the vegetable oil sat on top of the water, making two layers.

The next step was to put ten drops of red food colouring into the bottle and wait until they all sank to the bottom and rested in the water.

Now the fun part! We dropped in half an Alka-Seltzer tablet, put the lid on and watched a miracle happen…

It looked like a volcano had erupted – it was so awesome!!!

After we took the lid off, it made a fizz noise. It  sounded like when you take the cap off of a bottle off coke.

The reason it made an eruption was because it has a chemical reactions to make the red food colouring burst to the top. The gas in the Alka-Seltzer tablets react to the water and the gas that is produced wants to escape. The little gas bubbles push up through the water and oil, taking some of the food colouring with it and that’s why it sounds like coke when we took the cap off.

We turned the classroom lights off and tried it again, this time with SIX Alka-Seltzer tablets and the mixture went crazy! We put a torch underneath the bottle and it lit up like a real lava lamp.

Then Mrs Falconer left it over night to settle and we when we came back into school the vegetable oil was separated from the water again.

We learned that this is called Molecular Polarity! 🙂