Fun with Science at Home

Since the typical German refrigerator is the size of an American college student's dorm fridge, there isn't much room for storing drinks. I've been keeping my drinks "refrigerated" by just leaving them on the balcony, where the temperature has been consistently below freezing for the past week.

Though the beer holds up well, we find an interesting reaction when I open a new bottle of Diet Coke ("Cola Light over here").... as soon as I open it and pour, it immediately turns into a Coke Slushie.  See it here:

Herr J immediately recognized this as "supercooling" the liquid.  The concept is this:  a liquid's freezing point is the temperature at which the free molecules "want" to stop being free and "prefer" to get themselves into a tighter, crystalline formation (because we've taken energy -- measured as temperature -- away from them).  As soon as just one set of cooling moelcules forms a crystal, the others will start forming more crystals right next to the first one.  BUT, if you have a relatively pure liquid and don't disturb it during the freezing process, the free molecules just might hang out in their freer liquid state well below the temperature at which they would normally crystallize.

This is definitely something anyone can do at home... get the kids to like science by making a Slushie!  Wonder if Cool-Aid would work, or if that has too many particles in the water...

In fact, there are a number of neat examples on YouTube where people supercooled water.  In this one, the guy cooled water down to -21 Celsius!  Notice how gingerly he holds & pours the water out -- so as not to disturb it too much.  The disturbance ends up being the water coming into contact with the bowl itself, where it immediately freezes with a cool effect (sorry about the pun).

Then we have this shirtless (Dutch?) guy who is pretty excited about his discovery.  He also "pours" gingerly so the disturbance is the water hitting the ice cube.  "This is not an optical illusion, this is for real!" says the surfer-scientist.

Finally, in this example, we see the entire process of doing this at home.  The water is only cooled to a little below freezing point, so it doesn't crystallize as quickly as in the other videos.  However, you can see that all it takes is a tap on the bottle to get the whole chain reaction going.  And notice that some of the bottles did freeze outside rather than become supercooled (probably because they had extra minerals/particulates in them to get the freezing started)  Warning:  the creator felt compelled to use "Ice Ice Baby" as the audio track.  Mute is advised.