Did you know that oil and water are not the same density?
That is why oil and water don’t mix.
However, they will add up to something that’s even more fun.
It’s a lava lamp!
All you need are a few simple household items and a tall clear glass.
Density is the amount of matter in a given space. It is a measure of how tightly packed together the particles that make up a substance are.
Water is a bit more dense than oil.
This means that if we set up a system to float because of the difference in densities, the water will sink in the oil and the oil will float above the water.
- oil (we used baby oil and vegetable oil)
- food coloring
- Alka-seltzer effervescent antacid tablets
- tall glass or bottle
- adult supervision
- Fill the glass with 1 to 2 inches of water.
- Add your favorite food coloring.
- Fill the rest of the glass with oil but stop at about 1 inch from the top so that it won't bubble over.
- Drop an antacid tablet into the mixture and watch.
- Try using different sizes of alka-seltzer tablet.
- Try using different types of oil.
- Try mixing the different types of oil to get your favorite "lava" flow.
Alka Seltzer tablets contain 3 ingredients: aspirin (pain killer), sodium bicarbonate and citric acid.
When dropped into water, sodium bicarbonate and citric acid combine to form sodium citrate, carbon dioxide, and water.
This sodium citrate can neutralize stomach acid and this is why alka-seltzer is an antacid medicine.
During this process, carbon dioxide is created.
Because carbon dioxide has a lower density than water, it forms bubbles and flows to the top taking some dyed water along with it.
When the bubbles burst, the blobs of colored water sinks back to the bottom because it has a higher density than oil.
This goes on until all the ingredients in the tablet are used up.
Which oil is the best?
We started out using baby oil because it was clear and colorless.
It smelled nice and looked less oil-like.
However, the bubbles were plenty and very tiny.
They clouded up the solution very quickly and you could hardly see the big blobs of color characteristics in lava lamps (the picture below is exceptional among many many cloudy pictures).
The bubbles also felt very quickly through the oil back into the water.
You could miss them easily if you blinked.
Then we tried the traditional vegetable oil. It worked very well.
Big bubbles of colored water falling gracefully thorough the vegetable oil.
But the oil was yellowish although also clear.
Because we really liked the colorless look, we tried the third time by mixing small amount of vegetable oil with baby oil.
This time, the bubbles were a little smaller than using the vegetable oil alone, but they still looked amazing.
The colored bubbles also fell slowly and elegantly through the oil.
Although the oil mixture was slightly yellowis, it was still very pleasant.
It was combining the best of both worlds.
I think we have a winner!
Note: We found out that you don’t need a dark background and a backlight to make a spectacular lava lamp.
It is splendid the way it is.