Impress the kids with this little bit of science, or be a hit at the next party and entertain the guests with this pretty cool party trick! Turn science into magic with just a piece of string, an ice cube, a bit of water, and some salt. This awesome demonstration explains how and why salt melts ice and is a nifty activity to do in the classroom to accompany some rather dull theory.
THE DARE:
I dare you to lift a piece of ice with string (without tying a not)! Think it’s impossible? With a pinch of salt and a cup full of science, it can be done!
Experiment with Salt and Ice
This activity is suitable for all ages, toddlers will enjoy the “magic” and older students will appreciate the method in the madness. It is not a lengthy experiment, so it will not be able to be done as a lesson on its own if you are working with older kids. A few worksheets or accompanying theory will do the trick!
Here’s what you will need:
- A few ice cubes
- A glass of water
- A piece of string (about 30cm)
- Scissors
Instructions:
- Make sure your glass of water is full, almost to the brim
- Place one of your ice cubes into the water, allowing it to float
- Lie your string so that it hangs over the ice block and the glass
- Sprinkle on a layer of salt, so that the top of the ice cube and string is covered
- Wait about 30 to 60 seconds, and then lift the string holding each end
- Watch as the ice cube tags along!
The Science Behind It
When salt comes into contact with ice, it lowers the melting point of the ice. In this experiment, we add a thin layer to the top of the ice cube, which in turns melts a thin layer of the ice. The water in the glass is cooling down because of the ice block, and as it runs over the top of the cube, layers start to freeze again, covering the piece of string and “gluing” it in to place.
The question is, why does salt melt ice?
In a nutshell, salt is a great ice melter because it causes “freezing point depression.” This means that salt helps in lowering the freezing point and, consequently, the melting point of water (the main component of snow and ice). In its pure state, water freezes at 0°C or 32°F. By using salt, that freezing point can be lowered which forces the ice to melt and prevents the water from freezing or re-freezing.It must be noted, however, that salt alone can’t melt ice. It must first be combined with water to start the melting process. REFERENCE: http://www.kissner.com/why-does-salt-melt-ice/
There it is folks! I told you it was quite a nifty trick, right? Science is so wonderful in that nearly every resource we have at home has science to it, and can be used in experiments. My toddler got a real kick out of this “game” as he called it and loves the fact that he could mess around with salt, so there you go, a handy sensory activity too! ENJOY!
Much love - 
