Make your own lava lamp!
- A clear container such as a large glass or an empty soft drink bottle with the label removed
- Tap water
- Cooking oil such as vegetable or rice bran oil
- Soluble aspirin/Alka Seltzer™
- Food colouring
- Torch or battery operated light (optional)
- Fill approximately 1/3 of the container with water.
- Slowly fill the rest of the container with oil until the container is ¾ full. If the oil and water have mixed, wait for them to separate.
- Add at least 10 drops of food colour to the container. Wait until the food colour settles into the water.
- Break a tablet in half and drop one half into the container.
- Keep adding half tablets for as long as you like.
- If the container has a lid, you can keep the experiment and do it over and over for as long as you like!
- If you have a light/torch you can turn the overhead lights off and shine the torch through the container and watch the show in the dark!
- The oil settles above the water because oil is less dense than water. Although it is not entirely accurate, it may be easier for kids to understand if you explain that the oil is lighter than the water.
- The oil and water don’t mix because they are made of molecules that are not attracted to each other (you could illustrate this by using magnets and showing that when you try to push the same poles of the magnets together, they push away from each other. The oil and water are basically doing the same thing).
- When the tablet is added and sinks into the water it dissolves. As it dissolves a carbon dioxide gas is created. The gas is lighter than the oil and the water but some of the coloured water attaches to the gas bubble which then rise to the top of the oil. As the gas escapes from the liquid the blobs of coloured water sink down making the “lava lamp” effect!
For more exciting experiments why not grab our Chemistry-in-Action kit?