Making lava lamps

This week we decided to try to make a lava lamp! Our school takes part in the Discover Primary Science programme so we are using this experiment for both science and maths.
We had great fun doing this on Friday.

First we had to gather all the equipment. We needed 1L clear plastic bottles, vegetable oil, water, food colouring, effervescent tablets (Alka Seltzer), non effervescent tablets (Vit C) and measuring jugs.

Next we had to calculate how much of each we needed. We are all so good at fractions this was very easy for us to do! Then we used the measuring jugs to make sure we had the correct amount of water and oil.

Next we added food colouring. This does not mix with the oil but it does mix with the water. We used red and green food colouring. Finally we added the Alka Seltzer tablet and watched our lava lamps work! 

The chemical energy from the Alka Seltzer reacts with the water produces a gas called carbon dioxide. This gas travels through the oil and tries to escape from the top. This is why the bubbles travel through the oil to top of the bottle. We can see this happening because we dyed the water using food colouring. 

To reuse this lava lamp at any time just add another piece of Alka Seltzer