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Melt or Freeze…Which One Will it Be

You know that ice is the solid-state of water.

You also know that ice is cold and that if the temperature falls below freezing, the ice will begin to melt. But did you know…

What happens when ice melts

There are two things necessary in order for ice to melt: ice and above-freezing temperatures. When the ice starts to melt, though, the ice itself uses energy to do so. And that energy—the very same energy that is melting the ice—cools the ice off because that’s what happens when you use energy—you cool off.

It’s kind of like sweating. When you use up a lot of energy running, working, or exercising, your body temperature rises. But because your body knows it needs to stay within a certain temperature range, you begin to sweat to cool your body off.

Let’s take a look at how this works.

Here is what you need:

  • 4 to 6 ice cubes—take them from the freezer 1 at a time
  • 4 to 6 pieces of twine —about 8 inches long cotton baking twine or crochet thread will work fine
  • Small shallow bowl or saucer
  • Salt
  • Sugar
  • Pepper
  • Flour
  • Olive oil
  • Cinnamon

Here is what you do:

  • Lay one end of a piece of string on top of the ice cube and leave it there for about 30 seconds
  • Lift the string off the ice cube and take note of what happens
  • Lay the string back on the ice cube
  • Sprinkle about 1/8 of a teaspoon of salt on top of the ice cube; making sure you sprinkle the salt over the string, as well
  • Count to 30, lift the string, and take note of what happens
  • Get rid of the ice and the string
  • Repeat this process with the sugar, pepper, flour, oil, and cinnamon NOTE: You can choose which ones you use if you don’t want to use them all
  • Throw each ice cube and string away after each test

What happened:

The chemical makeup of the salt breaks down the bonds of the ice faster and with more intensity than the other items.

Because more energy was used to melt the ice with the salt on it, the quicker the ice-cooled itself—refreezing around the string.

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Facts for Kids

That is why you were able to pick up the ice with the string after salting the ice.

Try this

You might think that if this experiment works with salt, you could also pick up the ice cube with a string if you put hot liquid on an ice cube because it would melt the ice quickly too…like the salt. But does it work like that?

You can redo the experiment using hot tea or coffee—just be careful to not burn yourself.

What do you think will happen? Do you think the results will be different if you drip small amounts of the hot liquid on instead of pouring it on the ice cube all at once?

HINT: If the amount of heat the ice comes in contact with is too much, the ice will not be able to create enough energy to cool itself off at a rate fast enough to refreeze.