Levitating Ice Cubes

With this magical science experiment, you’ll impress your students as you make ice cubes dangle from a piece of string! Such a feat is sure to conjure up some serious questions about science, salt and magic from your class! Don’t worry, though - we’ll explain the reaction in the cup so you can handle the inquisitive, wide-eyed reactions of your kids.

Levitating Ice Cubes

What you will need

  • Clear cup
  • Ice cube
  • Salt
  • Food coloring (optional)
  • String

How to make it

  1. Fill the cup ¾’s full of water.
  2. Put a drop or so of food coloring into the salt to create magical, colored salt crystals. (We used green; with the addition of food coloring, the attachment of ice to the string will become more apparent.)
  3. Salts Crystals Dyed Green!

    Salts Crystals Dyed Green!

  4. Now, place the ice cube into the water.
  5. Pace the string inside the water and over the ice cube. Put on display the fact that the string does not stick to the ice cube.
  6. Once that idea is obvious to your class, sprinkle the colored salt onto the ice cube.
  7. Quickly place the string onto the ice cube and let it sit for about 2 minutes.
  8. Pull the string out of the water and show your students that the ice cube is now securely attached to the string, like magic!
  9. Levitating Ice Cubes

    Levitating Ice Cubes

What happened?

Salt lowers the freezing point of the water. Therefore, when the salt hits the ice cube, the ice cube begins to melt a little bit. After this reaction has occurred, the salt begins to weaken and becomes captured by the ice, freezing the thread to the ice cube.

Where do we see this reaction in our everyday lives?

Ever wonder why oceans never freeze? Since the salt compound found so heavily in the ocean controls the ocean’s freezing point, salt lowers water’s ability to solidify. Even when the temperature is zero degrees, oceans are still filled with salty water!

Also, have you ever wondered why people salt icy roads? This experiment must have made that a little clearer! We’ve shown that salt has the ability to melt ice. This is especially helpful in cold, snowy places where people walk or drive everyday, to keep paths and roads slip-free!

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