Ice Lifting
Materials
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Ice cubes
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Water
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Cups or glass
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Salt
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String
Instructions
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Place an ice cube on a cup of water.
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Cut a piece of string a few inches long.
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Dip the end of the string in the water and lay it across the ice cube.
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Sprinkle some salt on top of both the ice cube and the string. Wait a minute or so and then try to pick up the ice again using just the string.
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The ice will stick to the string.
What's the Science?
Due to the difference in temperature, when we place the ice into the glass with water, two things happen simultaneously: the ice starts melting and the water starts freezing. At this point, there is a state of equilibrium or balance.
Adding salt to the ice and string disrupts this balance. Salt water has a lower melting point and at the same time, the salt water gets more and more diluted into pure water. The water and ice are able to cool and re-freeze the water surrounding the thread, kind of “sticking” the string onto the ice and enabling you to lift it by the other end.
Tip
This phenomenon may also be used to stick ice together: create towers of ice blocks with layers of salt acting as glue!