Make a Salt Lava Lamp - Mad Science

Описание: Try this easy experiment at home - find out how below!

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Salt Lava Lamp: Step-by-Step

What you need:
Tall clear drinking glass
Vegetable oil
Water
Food coloring
Salt, 120mL (1/2 cup)

What you do:
Step 1: Place 1-3 drops of food coloring into the glass.
Step 2: Fill the glass two thirds of the way full with water.
Step 3: Slowly pour vegetable oil into the glass until you get a 2.5cm (1") layer of oil. Let the mixture settle until you have two separate layers.
Step 4: Slowly pour about 60mL (¼ cup) of salt into the glass in a circular motion.
Step 5: You now have a lava lamp! Watch as the salty lumps slowly form and rise to the surface. You can make more globs by adding more salt!

What's going on?
Everything is made of tiny molecules that we cannot see. Density is a measure of how many molecules are packed into a substance. Denser substances are heavier than less dense substances. Oil is less dense than water, which is why it floats on top. Salt is heavier than both water and oil, so it sinks to the bottom of the glass. As the salt sinks it pulls some of the oil down with it, trapping it at the bottom of the glass. As the salt dissolves in the water, the trapped oil escapes. It slowly rises back to the surface, creating the cool goopy lava lamp effect.

Now try this:
Try using different liquids. Do you get the same effect? Would different kinds of salt-like particles like sugar or sand give the same effect? Make your hypotheses and test them out!