Relevant Resource questions :

Concepts demonstrated :

• phase transformations

Equipment needed :

• Phase model of water

N/A

Accessories (ie posters etc) :

None.

Physics involved :

The model demonstrates the solid, liquid and gas phases of water for different conditions of temperature, pressure and volume.

How to use the Demonstration :

• Probably too small to use in a lecture unless it is passed around the theatre or used with a CCD camera.
• Would be better used in a tutorial.
• This demonstration should not be used for POE, rather as a lecturer's demo tool.
• Maybe there can be some POE brought into it or the issues around it.
• With the physical model, need to look at two dimensions only at a time.
• Molecular animation - link the demonstration to a visualisation of what the material is doing at the same time on the molecular level.

Things to do or add :

• Use computer animations.
• Lookup "Utectics" in the CRC handbook, you may find the data needed to construct a computer model. (-PW)
• Need to label zeros on the current model/diagram (T=0, V=0, etc). Make them as transparent axes.
• Check the correctness of the labelling of the phases on the current physical model e.g. the labelling of vapour and gas.
• Use a 3D model on a computer and rotate it with a mouse. This gives us the ability to:

  - slice the model for P=x, T=x etc.

  - only consider three main phases: solid, liquid, gas.

  - do the model for liquids e.g. alcohol, where as T decreases, V decreases also.

• Change the computer model to reflect water or alcohol, or do an ideal gas (PV= nRT), and then a correction for water freezing. CO2 (dry ice) is interesting because it sublimates at room temperature. Mercury (Hg) is interesting because it is a liquid at room temperature. Do the physical experiment using liquid nitrogen (LN2): drop a drop of Hg into LN2 so that it freezes, pick it up with tongs, place it on a watch glass and watch it return to liquid.
• Look at the Stirling Engine (heat engine). P and V change, but so does T, so do this in 3D as a computer model.

• How do other lecturers use this demonstration?
• This is a poor demonstration. The colours on the current model are poor.
• The triple point line on the current model is confusing.