Room 4 Scientists

Try some lava in a cup

What we used:

A clear cup

¼ cup of vegetable oil

1 to 4 teaspoons of salt

Water

Food colouring

What we did:

1. Fill the cup about ¾ cup full of water

2. Add about 5 drops of food colouring

3. Slowly pour the oil into the cup. See how the oil floats on top

4. Sprinkle the salt on top of the oil

5. Watch blobs of lava move up and down in your cup!

6. Add another teaspoon of salt to keep the effect going.

How does it work?

It looks a bit like a lava lamp because the oil floats on top of the water because it is lighter than the water. Since the salt is heavier than oil, it sinks down into the water and takes some oil with it, but then the salt dissolves and back goes up the oil!!!