Check out this super easy DIY lava lamp experiment! In just 15 minutes, you can learn the science behind lava lamps!
Materials:
Mason jar or plastic bottle, Alka Seltzer Tablets, vegetable oil, water, food coloring (optional)
Time Estimated:
10-15 minutes
Directions:
Fill the container most of the way with vegetable oil.
Fill the rest of the container with water. The water will sink to the bottom under the oil.
Pick your favorite color and add a few drops of food coloring!
Break an Alka Seltzer tablet into a few small pieces, and drop them in the flask one at a time… and… watch your lava lamp erupt into activity!
Think Like A Scientist:
What if you use multiple colors of food coloring?
What if you add extra Alka-Seltzer tablets?
How It Works:
A lava lamp works because of two different scientific principles: density and polarity.
Density is the measurement of how compact a substance is - how much of it fits in a certain amount of space.
If you measure an equal volume of oil and water, you'll find that the water is heavier than the same amount of oil. This is because water molecules are packed more tightly; a cup of water actually has more mass than a cup of oil. Because water is more dense than oil, it will sink to the bottom when the two are put in the same container. Density is affected by temperature—the hotter a liquid is, the less dense it will be.
Polarity prevents the oil and water from mixing together.
Water molecules are "polar" because they have a lopsided electrical charge that attracts other atoms. The end of the molecule with the two hydrogen atoms is positively charged. The other end, with the oxygen, is negatively charged. Oil molecules, however, are non-polar— they don't have a positive or negative charge, so they are not attracted to the water molecules at all. This is why oil and water don't mix! Real lava lamps use a polar and nonpolar liquid just like our homemade one did. In a real one, however, the densities of the liquids are much closer together than vegetable oil and water. In our homemade lava lamp we used alka-seltzer to power the lamp. The alka-seltzer reacts with the water to produce carbon dioxide gas bubbles. These stick to the water droplets. The water/gas combo is less dense than the oil, so they rise to the top of the mason jar. At the top, the gas bubbles pop and escape into the air, allowing the dense water to sink back to the bottom again.
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