Today I made a test tube crystal ball. This is what I did.
1. I filled a test tube half full of cooking oil.
2. I put in some water in the test tube and saw that the oil floated on top of the water. That is because oil is less dense than the water. Things that are less dense float on top of things that are more dense.
3. Next I added more warm water and filled the tube.
4. I added a blue colored tablet to the tube. The color tablet sank to the bottom of the water because it is more dense than the oil and water. The blue color tablet started bubbling like lava in the oil. Why did it bubble? Because inside the color tablet is baking soda and citric acid. The baking soda and citric acid react when they hit the water at the bottom of the test tube making carbon dioxide bubbles that are less dense than the water or oil. These bubbles attach themselves to drops of the blue colored water and carries them to the top of the test tube. When the bubbles get to the top, they pop! The colored water droplets sink back down to the bottom making the test tube a bubbling crystal ball.
5. After the bubbles were all gone, I put the top on the test tube and shook it up. The colored water swirls around in the oil, then it settles again. My mom says it is like a lava lamp from the 1970's!
I had a lot of fun doing this experiment.
