When I asked the boys if they think they could pick up an ice cube with a string, they both thought I was crazy. “No, you can’t!”, “There is no way you could do that!” were just some of the comments I was getting. So off we went to try to see if we could actually lift an ice cube on a string.
To do this experiment, you will need:
cup of room temperature water
cotton, yarn or twine
Cut a piece of string or yarn about 15 cm (6 Inches) long.
Place a couple of ice cubes in the glass / cup.
Our boys then placed the string on an ice cube to see if they could pick it up. They couldn’t.
Now dip the string into the water to wet it, then lay the string across the top of an ice cube.
Using the teaspoon, sprinkle a generous amount of salt on top of the string/ice cube.
Wait about 1-1 1/2 minutes and try to lift the string out of the water. This time it should work.
The boys had a great time with this experiment and did it over and over again
trying to see who could lift their ice the highest and who could hold their ice on the string for the longest.
We also found that our ice cube spun like crazy when we first pulled it out of the water, but eventually slowed down to a gentle back and forth rock.
How does this work?
Normally ice melts at 0˚C (32˚F). When the salt is added, it lowers the temperature that the ice melts at and the water can freeze. So, the salt around the string begins to melt the ice while taking the heat from the surrounding water. The cold water then refreezes around the string, allowing you to lift it from the water.