MAGIC ICE

Learn how salt lowers the freezing point of water.

Freezing Point - the temperature at which a liquid becomes a solid.

Glass of water filled 6 inches
String, 6 inches long
Three ice cubes
Spoon
Salt, 3 tablespoons
Sugar, 3 tablespoons
Pepper, 3 tablespoons

   1.  Place one ice cube into the glass of water.

     2.  Lay one end of the string over the top surface of the ice cube.

     3.  Sprinkle sugar onto that end of the string and the area around it.

     4.  Wait 1 minute. Gently try to lift the ice cube out of the water with

            the string.

     5.  Repeat with a clean glass of water. Try the pepper and then salt.

     6.  What happened?

How does it work?

Only the salt lowers the freezing point, causing the ice to melt.  As the ice melts, enough heat leaves the ice cube to freeze the string onto the cube. That is why salt (not sugar or pepper) is sprinkled onto icy roads.  Some schools and businesses put salt on their icy sidewalks.

Questions to ask:

1. Will the string stay on the ice cube without salt on it?  Try it?

2. If you let the ice cube melt in the sun, will the string stay on the ice cube?

Science Projects