Everyday Chemistry
Lesson 2: What's the difference?
Fun Experiment 2 - Homemade Lava Lamp
Here's an easy way to make a version of a Lava Lite, or Lava Lamp. Lava Lites are lamps that were invented by an English man named Craven Walker in 1964. They are basically tall thin glass jars filled with liquid and a special kind of colored wax, set on top of a base with a light bulb. When the bulb is turned on, the lamp glows, the liquid heats up, and the wax begins to melt. Blobs of wax rise to the top of the lamp, then cool and sink back down--over and over again. What You Need:
Here's How:
Details Behind The Experiment: Why does the oil float on the water? Oil floats on water because a drop of oil is lighter than a drop of water the same size. Another way of saying this is to say that water is denser than oil. Density is a measurement of how much a given volume of something weighs. Things that are less dense than water will float in water. Things that are more dense than water will sink. Even though oil and water are both liquids, they are what chemists call immiscible liquids. That's a fancy word that means they don't mix. What happens when I pour salt on the oil? Salt is heavier than water, so when you pour salt on the oil, it sinks to the bottom of the mixture, carrying a blob of oil with it. In the water, the salt starts to dissolve. As it dissolves, the salt releases the oil, which floats back up to the top of the water. This looks like a Lava Lite. How does a Lava Lite work? Like your oil and water, the "lava" in a Lava Lite doesn't mix with the liquid that surrounds it. When it's cool, the "lava" is a little bit denser than the liquid surrounding it. When the "lava" rests on the bottom of the Lava Lite, the light bulb in the lamp warms it up. As it warms up, the "lava" expands a little. When it expands, the "lava" stays the same weight but it takes up more space-so it's less dense. When it's warm enough, the "lava" is less dense than the surrounding liquid, and so it rises up to the top to float. At the top of the lamp, it cools down, becomes more dense, and sinks once again. This cycle repeats over and over as the "lava" warms up and rises, then cools down and sinks. Where did this experiment come from, anyway? Exploratorium Teacher-in-Residence Eric Muller created this activity while playing with his food in a Chinese restaurant. Experiment found at:
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