Chemical Concept Demonstrated

• Charles' Law

Demonstration

A flask is filled with water and stoppered. A thermometer is inserted through the hole in the stopper, and a syringe is inserted through the stopper. Immerse the flask in a ice-water bath to lower its temperature. Record the temperature and the volume of the gas in the syringe as the gas warms to room temperature.

Observations

As the gas warms from the ice-water bath  to room temperature, the volume of the syringe increases.

Explanation

A gas expands when it is heated and condenses when it is cooled.  As the flask is warmed from 0ºC to room temperature (25°C), the gas expands inside the flask and slowly moves the syringe plunger.  This demonstration demonstrates the relationship between temperature and volume (Charles' Law), and can be used to extrapolate absolute zero.

Contributors

• Dr. George Bodner (Perdue University)