How to Make a Lava Lamp Experiment

Practically everyone understands the one major and most obvious characteristic of the lava lamp that makes it a lava lamp--water and oil don't mix together. However, there are some other physical properties in action at the same time. This is a fun and easy lava lamp experiment that you can do with your kids. You probably have everything you'll need in your home, and the youngsters will be amazed at your scientific genius.

Things You'll Need

• Plastic 16-oz. soda bottle with tight-fitting lid
• Lowest-quality vegetable oil that you can find
• Water
• Food coloring
• 1 Alka-Seltzer tablet

Instructions

1. Break the Alka-Seltzer tablet into eight small pieces, and set them aside.

2. Pour about 12 oz. of vegetable oil into the empty plastic bottle. It will be ¾ full. Add enough water to almost fill the bottle, leaving about ½ inch unfilled at the top. Explain to the kids that the water will sink to the bottom of the bottle because it's heavier than the oil.

3. Squeeze a few drops of food coloring into the bottle. Point out to the children how the coloring combines only with the water, because it is water-based. Neither the water nor the food coloring will mix with the vegetable oil. Add more drops of food coloring until the shade of the water becomes as deep as you want.

4. Cap the bottle tightly and have the kids flip it upside down, flip it right side up again and even shake it up vigorously. Note that the oil breaks up into small drops and the colored water moves around in a big blob that looks like lava, but it still won't mix with the oil.

5. Remove the cap from the bottle and drop a piece of the Alka-Seltzer tablet into it. Explain to the kids that the tablet is making little colored water bubbles that contain carbon dioxide gas as it reacts with the water. Because the gas is lighter than both the water and the oil, the bubbles will make their way to the surface. When they pop, the gas is released into the air, and the bits of broken bubbles will sink back into the water below.

6. Amuse the youngsters a little while longer by dropping the remaining bits of Alka-Seltzer into the lava lamp one by one. When they're through, cap the bottle tightly.