Supercooling

Most substances have a freezing point, the temperature at which a substance transitions from a liquid to a solid. However there is an effect known as supercooling in which a liquid's temperature may drop below the freezing point yet still remain a liquid. This is due to the fact that in order for a liquid to freeze, its molecules have line up into a crystal lattice. However, starting such a lattice requires a nucleation site, where a few molecules can lock together and start the freezing process. A nucleation site could be as simple as a grain of dust or a scratch on the surface of the container. But if a liquid is placed into a very clean container that does not have nucleation site, then the liquid could supercool. In the supercooled state, as soon at it is disturbed too much or it meets a particle of the frozen substance then the freezing process begins a chain reaction, leading to all of the liquid freezing at once.

Supercooling can be demonstrated in your own home using bottled distilled water.

What you need:
-A freezer
-5 or more bottles of distilled water
-Time

What you do:
1. Place a bottle of water in the freezer.
2. Check on it every 15 minutes after the first hour.
3. Wait for the time when the water has frozen.
4. Put in the other bottles of water in the freezer.
5. Take them out 15 minutes before the trial run bottle had frozen.
6. Any bottles with liquid water should be supercooled. Give it a hard whack or pour it onto an ice cube to begin the freezing process.

This makes the process sound simple, but in reality there are a lot of things that make it so that it doesn't supercool. If it doesn't work, keep trying!

Image Citation: Super Cooled Water. N.d. Http://www.askamathematician.com. Ask a Physicist. Web. 9 May 2016. <http://www.askamathematician.com/2012/11/q-could-kurt-vonegets-ice-9-catastrophy-happen/>.