Ice Fishing
Aim/Purpose:
To see how salt can affect ice or react with ice
Materials
- Small paper cups, bowl or an ice cube tray
- Glass of water
- String (yarn or kite string works great)
- Small stick
- Salt
Steps/Method:
- Fill the cup or tray up with water and place it in the freezer. You can also use ice cubes from your freezer and skip this step.
- When the water is frozen, remove the ice from the cup or tray.
- Put the ice in the glass or bowl of water. The cube will bob up and down in the water and then float on the top.
- Place one end of the string from the fishing pole on top of the ice cube and sprinkle salt on the ice where the string is touching. Watch as the water melts slightly and refreezes.
- After about 10 seconds, carefully lift the ice cube out of the water with the fishing pole. You caught a fish (ice)!
My results:
Salt - The string stuck really well to the ice and pulled the ice cubes up out of the water
Sugar - The string didn’t stick to the ice cubes and none of them were pulled up out of the water. Some people started to see the ice cubes stick - but it then failed after that.
Flour - THe ice didn’t stick to the string at all
Pepper - The ice didn’t stick to the string at all
More salt than normal - The ice still got picked up by the string
Explanation - Why does it work?
Ordinary water freezes 0° celsius. But when you add salt to this it lowers the freezing water’s temperature. This simply means the ice melts. The salt you sprinkle on the ice cube lowers its freezing temperature and, since the ice cube can’t get any colder than it already is, it starts to melt. A little pool of water forms on top of the ice cube and the string sinks into it. As the ice cube melts, it decreases the salt mixture in the little pool; the freezing point starts to go back up again. The ice refreezes, trapping the string. So then as soon as the ice cube hardens, you can raise it by lifting the string. This is why it works.
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