Salt Lava Lamp

Overview:

This activity is to make lava lamps.

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.

Skills required by staff:

Base setup:

How to run the base:

What you do:

1.         Pour about 3 inches of water into the jar.

2.         Pour about 1/3 cup of vegetable oil into the jar. When everything settles, is the oil on top of the water or underneath it?

3.         If you want, add one drop of food coloring to the jar. What happens? Is the drop in the oil or in the water? Does the color spread?

4.         Shake salt on top of the oil while you count slowly to 5. Wow! What happens to the food coloring? What happens to the salt?

5.         Add more salt to keep the action going for as long as you

Possible expansions to the activity: