Description
In a reduced pressure atmosphere, water will boil below its "normal" boiling point.

Application
First day demo Gas Laws Phase Changes

Theory
As ice water is poured over a flask of boiling water, some of the vapor inside the flask condenses. This decreases the pressure over the water inside the flask. The decreased pressure on the water allows it to boil at the temperature below its normal boiling point of 100°C.

Materials
500 mL Florence flask Hot plate
Stopper with thermometer inserted in it Clamp
Ice water

Safety
Wear protective gloves and safety goggles.
Use a Pyrex flask..

Precautions
Wear safety goggles..

Preparation
Ice Add food coloring to 350 mL water

Demonstration
Fill flask half full with water.

1. Heat water until it boils.
2. Place stopper with thermometer inserted on the flask.
3. Remove the flask from the heat and invert it.
4. Pour the ice water over the flask.
5. Observe the water boiling again. Note the temperature.
6. Continue pouring the water and observing the temperature of the 'boiling' water.

Disposal
Solution may be poured down the drain and flushed with water.

Reference
Prentice Hall, Chemistry the Study of Matter.