Eduard-Job-Foundation for Thermo- and Matterdynamics

Experiment 5.4: Causing Warm Water to Boil by Cooling

Experiment: Boiling by Cooling

Ice water is poured over a round-bottomed flask filled with warm water (and water vapor).

The water begins to boil heavily.

The boiling process can be described by 


Liquid water has a smaller chemical potential than water vapor under standard conditions (298 K, 101 kPa), i.e., the process will not take place spontaneously.

But the chemical potential of gases and therefore also that of water vapor is strongly pressure dependent shown by a high pressure coefficient β. At sufficiently low pressure (here caused by condensation of water vapor) the chemical potential of water vapor will fall below the value of liquid water so that the water boils at temperatures significantly less than 100 °C.

Video (mpg4, 0:40)