We love watching the bubbles in a lava lamp dance. But before they get their groove on, there’s a lot of chemistry that has to happen!
When you add the oil and water to your bottle, you’ll see that the water sinks to the bottom and the oil sits on top. Try shaking up the bottle (don’t forget to put the cap on) and see what happens. No matter how hard you shake, the oil and water won’t mix together — they’ll always separate out again!
There are two reasons that oil and water don’t mix. The first reason has to do with something chemists call polarity. Water is made up of polar molecules. That means each molecule has a positive charge on one end and a negative charge on the other end. Positive and negative ends stick together kind of like magnets. Oil is made up of non-polar molecules. That means they don't have a positive or negative charge. Since the water molecules are looking for a positive or negative charge, they won’t mix with the oil molecules. The second reason has to do with something called density. The denser something is, the more stuff there is packed into it. If you weigh a cup of water and a cup of oil, the water weighs more. That means the water is more dense than the oil, which is why it sinks to the bottom!
But there are ways that you can mix them up! Adding the fizzy tablet will create a chemical reaction that causes carbon dioxide gas bubbles to form. Water droplets will stick to the bubbles and hitch a ride to the top of the bottle. Once the bubbles escape, the water droplets will sink back below the oil. It is a density disco, polarity party, and a bubbly ballet all in one!
Gather your materials.
Fill the container ⅘ full with vegetable oil.
We used a funnel, but it’s not necessary!
Fill the rest of the container (almost to the top!) with water. If the container is too full it might overflow when you add the fizzy tablets!
Add a few drops of food coloring. They should sink to the bottom of the container and color the water.
Break up a fizzy tablet and drop it into the container and watch your lava lamp come to life!
Want to experiment more? Try making a glow-in-the dark lava lamp. Instead of tap water, use quinine water (aka tonic water) and no food coloring. Place your lava lamp under a blacklight to light it up!
A bubbly lamp!
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