Monday, November 11, 2013

Fishing For Ice

Have you ever lived in or visited a snowy place in the winter? Have you ever wondered why salt is spread over the roads after it snows or why people sprinkle salt over their stairs and walkway when they get icy? Well wonder no more because we are going to answer those very questions right now.

When salt is mixed with ice it lowers the freezing point. Usually water freezes at 32° F (0° C), but when it is mixed with salt it lowers the freezing point significantly. This simply means the ice melts. We have used this same trick to make yummy treats like fruity ice slush and easy homemade ice cream!

For our experiment today we will use this phenomenon to do a little trick I like to call "Fishing for Ice".
Total Time: Less than 5 minutes
Difficulty: This may be the easiest experiment we have done so far, which is saying a lot since most of our experiments are very easy.

Materials You Need:
Cup full of water
A few ice cubes
Table salt
A piece of string

  • Place the ice cubes in the cup of water. They will float on top.
  • Try to "fish" for an ice cube with the string. It won't "catch" anything.
  • Place the string in the water and across the top of the ice cubes. 
  • Now sprinkle a little bit of salt across the ice cubes. Wait for a minute or so.
  • Pull the string out and see what you caught!
When salt is sprinkled over ice it melts. However, when it is used in such a small amount, like in our experiment, the water around the ice freezes again quickly. This means that the string gets trapped as the water around it freezes, thus making it stick to the ice. We were able to freeze all of our ice cubes to one piece of string. How about you?

Print These Instructions

*Note: In the video we put salt in first and then tried to "fish" with the string. It may work better if you put the string across the ice cubes first and then sprinkle some salt on top of the ice and the string, as mentioned in the directions. Let us know how it works for you!

1 comment:

  1. This looks so easy and fun! I love finding simple things to teach my kids. (I usually learn as much as they do!)


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