This can be used to show :-

     - the expansion and contraction of heated gases

     - the boiling of reduced boiling point of water at lowered pressure

     - the action of indicators with acids and bases 

Figure 1 - Pipette tube placed through rubber stopper.

Figure 2 - The apparatus ready to go.

Figure 3 - The fountain flows!

1. Before the lesson insert the long nosed pipette through the hole in the stopper so that the fine end will end up about one third of the way into the boiling flask. (See figure 1)
2. Place about 100 ml of water and a few drops of the NaOH into the boiling flask and just bring to the boil
3. In the beaker have 500 ml of water, ice cubes, a few drops of the HCl and phenolphthalein.
4. Once just off the boil place the stopper in the flask and carefully turn upside down.  Clamp the inverted flask on the retort stand.  A thick cloth may be needed here, to help lifting the hot flask.

5. Lower the flask so that the pipette tube goes into the cold water and watch

    the colourful fountain.

The water that initially boiled filled the flask with water vapour forcing out the air.  As this vapour cools it condenses creating a partial vacuum.

This vacuum slowly draws the cold water from the beaker up into the flask.  This introduction of cold water speeds the process until a strong fountain is spraying in the flask.  The phenolphthalein reacts with the NaOH, turning pink.  

You may also notice that as the cold water first starts flowing strongly the hot water in the flask starts to boil again.  This is because the water boils at lower temperatures when it is at reduced pressure.

This Wizard was suggested by Mr. Chris Reed (Thanks Dad)