A few weeks ago, we showed you how to make a homemade lava lamp. This is a simpler way to create a lava-like appearance in a cup. If you missed our last lava lamp blog, check it out here: http://discoveryexpress.weebly.com/homeblog/make-your-own-lava-lamp
- Heat absorption
Look up the definitions for the key words at dictionary.com prior to reading about liquid motion lamps (lava lamps).
Why don’t oil and water mix?
Check this link for an explanation of how traditional lava lamps work: http://science.howstuffworks.com/innovation/science-questions/question36.htm
- How many liquids are in a lava lamp?
- What qualities do these liquids need to have?
- Why do liquid motion lamps need heat?
- When heat is applied to a liquid motion lamp, what happens to the heavier liquid?
Last time you made a lava lamp, you added Alka-seltzer to your mixture of oil and water. The Alka-seltzer reacted with the water and produced carbon dioxide gas, which then created bubbles of water that floated to the top through the oil and burst, causing the water to sink back down (since water is a denser liquid than oil, it will always sink back below the oil). This created the illusion of a traditional lava lamp, or liquid motion lamp, which you already know uses heat to alter the densities of the two liquids in the lamp.
Once again, you are going to create an altered version of a lava lamp. This time, you will not be using carbon dioxide gas to create the illusion of lava, but instead will use salt. Salt? How would salt help you create a lava lamp? Let’s find out!
- A clear glass
- Vegetable oil
- Food coloring
Here’s what to do!
- Pour half a cup of water into the clear glass.
- Add half a cup of oil to the glass of water.
- Squeeze about 10 drops of food coloring into the oil/water mixture. What happens? Write down your observations. Is the oil colored? How about the water? Why do you think this happened? Draw a picture of what your glass looks like right now. Use a marker to illustrate where the colored liquid is.
- Now for the fun part! Sprinkle about a teaspoon of salt on top of the oil in the glass. The lava action begins! Watch what happens and record your observations.
- Why did salt cause the oil in the glass to sink? Salt is heavier than oil. When you add salt to the glass, it sinks through the oil but causes some of the oil to sink below the surface of the water with the salt. Once the salt dissolves in the water, the oil that was attached to the salt floats back up to the surface of the water where it should be.
- Once the “lava” stops moving, sprinkle more salt into your glass to keep your lava in a cup going strong!
- Experiment with different levels of salt, water, or oil. How does this affect how well the lava functions?