Room 8’s Amazing Trick

Can you pick up ice with a piece of string?

Impress people with this trick!

Try picking up a piece of ice with a string. Can you do it without tying any knots?

Room 8 will show you how!

What you need is:

  • Ice cube
  • Salt
  • String
  • Glass
  • Water
  • Scissors

How we did it?

  1. We have filled a glass to the top with water (we added some food colouring for more fun).
  2. We have chosen a piece of colourful string around 20 centimetres long.
  3. We have placed an ice cube in the water. What have we observed? It has floated. Anything else? Of course. The ice cube has been cold.
  4. We have laid the string across the ice cube and glass. Nothing has happened.
  5. We have tried a magic trick: we have covered the ice cube and string with a layer of salt (we have tasted it also). Oh, no! Very salty!!!
  6. We have left them for 10 seconds – we have counted the seconds.
  7. Carefully, we have pick up the ends of the string and what do you think? Magic. We managed to lift up the ice cubes! Wow! Well done, Room 8!

What’s happening?

Salt lowers the freezing point of water to below 0 degrees Celsius. When we added salt to the ice cube, the salt lowered the melting point of the ice. The salt is in a thin layer, so it melts a thin layer on top of the ice cube. The water cooled down further and re-froze around the string.

Now we understand why Ray, our janitor, uses salt in winter to prevent the road and our playground from getting icy and dangerous.

It is you turn now! You could challenge your friends and parents. See if they can work out how you did it. Good luck!

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