Ask the students to explain their observations. After the demonstration turn the flask right side up and remove the stopper to equalize the pressure. If the stopper that is inserted into the flask is fitted with a thermometer, the temperature at which the water boils can be determined. The class should be asked to define boiling and boiling point. If only the polarity of water is to be shown, produce a fine stream of water from an available water faucet and have a source of static electricity.
Water is a common substance but one with special properties.
Much is usually said about the polarity or non-polarity of molecules in chemistry. Following the demonstration, the shapes and structures of the molecules of the liquids can be related to their polarity. From this starting point, depending on when in the course the demonstration is used, the teacher may develop further ideas on the structure of molecules and their shapes or deal with the properties of liquids and solutions. Fill each burette with a different liquid. Open the stopcock of the first burette and let the liquid flow out into a receiving beaker with a fairly fine stream.