Boiling Water with an Ice Cube! (Demonstration)
(Reference: Bill Snyder, Columbiana, Ohio.)
 

Boiling point : pressure
 

Purpose:
Illustrate the idea of condensation of water creating decreased pressure in a system.
 

Safety:
Safety goggles, and heat resistant gloves

 
Materials:
Florence flask, 750 mL
Hot plate
Stopper
Ice
Heat resistant gloves
Ring stand
Ring clamp  (If you don't have a stand or a clamp, you can hold it yourself.)

 
Procedure:
Place about 300 mL of water in Florence flask.  Heat until boiling rapidly. Remove from heat and stopper immediately (in front of class).  Be sure you are wearing the gloves!  Let sit for 1 minute (no longer).  With mit, invert the flask into the ring stand.  Rub ice over the bottom and lower sides of the flask until water boils vigorously (about 15 seconds).
 

Explanation:
As the water vapor inside the flask cools (from the application of ice), it condenses, lowering the pressure.  The water is still warm enough to boil at this lower pressure, and does!
 

Clean-up:
Gently pry the stopper off, and all solutions can go down the drain.
 
 

Ginger Chateauneuf, 2000.
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