Why Salt Melts Ice

Fishing for ice is a fun, easy, and quick kitchen science experiment. Learn how salt melts ice and why people spread salt on their icy stairs and walkways during the winter. Usually water freezes at 32° F (0° C), but when it is mixed with salt it lowers the freezing point significantly. This simply means the ice melts. 

For this experiment use this phenomenon to do a little trick call “Fishing for Ice”. 

Reward: Shake Up Bronze!

Why Salt Melts Ice

  • Cup full of water
  • A few ice cubes
  • Table salt
  • A piece of string
  1. Place the ice cubes in the cup of water. They will float on top.
  2. Try to “fish” for an ice cube with the string. It won’t “catch” anything.
  3. Place the string in the water and across the top of the ice cubes.
  4. Now sprinkle a little bit of salt across the ice cubes. Wait for a minute or so.
  5. Pull the string out and see what you caught!
Why Does the Ice Stick to the String?

When salt is sprinkled over ice it melts. However, when it is used in such a small amount, like in this experiment, the water around the ice freezes again quickly. This means that the string gets trapped as the water around it refreezes, making it stick to the ice. You are going to be able to freeze all your ice cubes to one piece of string.



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Fuente: The Science Kiddo