1. Sketch Andrew’s isothermal graph of pressure against volume for a real gas.
2. Sketch Andrew’s isothermal graph of pV against p for a real gas
2. Explain the term “isotherm”
3. Describe and explain the shape of a high temperature isotherm on Andrew’s p vs v graph.
4. An A-level text book suggests this information about carbon dioxide – “it is virtually impossible to liquefy carbon dioxide by pressure alone if the temperature of the gas is above about 31oC” – explain the significance of this statement with reference to your sketch graph.
5. Explain the terms “critical temperature”, “critical pressure” and “critical isotherm”.
6. Annotate sketch graph 1 with the main features for Andrew’s isothermals for p against V for a real gas. (if you haven’t already)
7. Explain the term “Boyle temperature”. Explain the main feature of real gas behaviour with reference to pV against p curves for an Andrew’s isothermal that is above the Boyle temperature.
Use the kinetic theory model to help describe and explain the main
feature of the sketch graph in question 2 for an isothermal that is below the
1. Define absolute zero
2. Explain how evaporation causes cooling.
3. Explain how a refrigerator works – in principle
4. What is the lowest temperature possible in a refrigerator determined by?
5. Define adiabatic expansion – explain how it can cause cooling.
6. Describe the Joule-Kelvin effect. Draw a diagram of the apparatus to illustrate your answer.
7. Sketch a graph of the results of a Joule-Kelvin investigation – and use this graph to describe the required conditions before the Joule-Kelvin effect can be used to cause cooling. Explain the significance of the “inversion temperature”.
Describe a practical arrangement that makes use of the Joule-Kelvin
effect to liquefy hydrogen. Explain
the importance of the “countercurrent
heat exchanger” and explain why
Hydrogen needs to be pre-cooled.
1. Below 2.17K Helium exhibits “superfluid behaviour” describe some examples of this.
2. Sketch a suitable graph to illustrate the lambda point of Helium. Explain the significance of the lambda point.
3. Sketch a graph to illustrate the variation of
Give examples of Metals,
alloys and compounds as superconductors, and explain the terms
critical temperature and current density for a superconductor.
5. Describe the term “high temperature superconductor” and suggest possible applications.