Ice Fishing experiment

Ice Fishing 

http://www.sciencefun.org/kidszone/experiments/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:

1. 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.
2. When the water is frozen, remove the ice from the cup or tray.
3. 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.
4. 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.
5. 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

Changing the variables

Don’t wet the string beforehand 

Use only a little salt

Using lots of salt 

Try to catch the ice using sugar instead of salt 

Try to catch the ice using pepper instead of salt

Try to catch the ice using flour instead of salt

Change the time period that you wait before trying to pick up the string.

Explanation - Why does it work?

The salt you sprinkle on the ice cube lowers its freezing temperature and the ice cube can’t get any colder than it already is, so 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/water mixture in the little pool; the freezing point starts to go back up again. The ice refreezes, trapping the string. As soon as the ice cube hardens, you can raise it by lifting the string. All this happens very quickly of course.