You will need
- A clean 1 liter clear soda bottle
- 3/4 cup of water
- Vegetable Oil
- Fizzing tablets (such as Alka Seltzer)
- Food coloring
What to do
- Pour the water into the bottle.
- Use a measuring cup or funnel to slowly pour the vegetable oil into the bottle until it’s almost full. You may have to wait a few minutes for the oil and water separate.
- Add 10 drops of food coloring to the bottle (we like red, but any color will look great.) The drops will pass through the oil and then mix with the water below.
- Break a seltzer tablet in half and drop the half tablet into the bottle. Watch it sink to the bottom and let the blobby greatness begin!
- To keep the effect going, just add another tablet piece. For a true lava lamp effect, shine a flashlight through the bottom of the bottle.
How does it work?
To begin, the oil stays above the water because the oil is lighter than the water or, more specifically, less dense than water. The oil and water do not mix because of something called “intermolecular polarity.” That term is fun to bring up in dinner conversation. Molecular polarity basically means that water molecules are attracted to other water molecules. They get along fine, and can loosely bond together (drops.) This is similar to magnets that are attracted to each other. Oil molecules are attracted to other oil molecules, they get along fine as well. But the structures of the two molecules do not allow them to bond together. Of course, there’s a lot more fancy scientific language to describe density and molecular polarity, but maybe now you’ll at least look at that vinegrette salad dessing in a whole new way.
When you added the tablet piece, it sank to the bottom and started dissolving and creating a gas. As the gas bubbles rose, they took some of the colored water with them. When the blob of water reached the top, the gas escaped and down went the water. Cool, huh? By the way, you can store your “Blobs In A Bottle” with the cap on, and then anytime you want to bring it back to life, just add another tablet piece.
MAKE IT AN EXPERIMENT
The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:
- Does the temperature of the water affect the reaction?
- Does the size of the bottle affect how many blobs are produced?
- Does the effect still work if the cap is put on the bottle?
- Does the size of the tablet pieces affect the number of blobs created?
IntroductionHave you ever seen a lava lamp? They were the height of 1960's "groovy" room decorations. A few minutes after turning it on, a lava lamp has blobs of colored liquid floating towards the top of the lamp and then drifting back down. Making an actual lava lamp that you plug in would require some effort and unusual supplies, but you can create a non-electric version in just a few minutes with the help of the fizzing power of Alka-Seltzer. In this activity you can find out how to make your own Alka-Seltzer® lava lamp. How will changing the temperature of the ingredients change the behavior of the colorful blobs in your lava lamp?
Teisha Rowland, PhD, Science Buddies
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,150 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
- Tall identical jars or bottles, such as empty, clear, plastic 1-liter or 2-liter bottles (2)
- Cutting board
- Timer or clock that shows seconds
- Food coloring
- Vegetable oil (enough to fill the jars nearly full)
- An Alka-Seltzer tablet. Only one tablet is needed for the activity, but having additional tablets can be fun if you wanted to repeat lava lamp action.
- A way to make one jar hot and one cold, such as by using a large bowl filled with hot water and access to a refrigerator or freezer