Figure 11.1 A generic PT phase diagram
§11.3, §11.4 The solid <==> liquid and liquid ¤ gas transitions: Although we refer to these transitions in the same manner, and they are both represented by the crossing of a single line in Figure 11.1, they are physically very different processes. We will find that we need to develop quite different microscopic models to understand each type of transition.
For the solid <==> liquid transition we test the Lindemann hypothesis that the phase transition occurs when molecular vibrations reach a certain amplitude. For the liquid <==> gas transition we develop the cell model of a liquid and its vapour pressure (§9.8) and find a connection between the microscopic parameters of the cell model and the latent heat of vaporisation.
§11.5, §11.8 The critical point and triple point: Examining the data on these points reveals that they occur at similar relative positions on the phase diagrams of quite different substances.
§11.6 Scaling: laws of corresponding states: Throughout this book, we have discovered correlations between the physical properties of different substances. This raises the hope that we might be able to use some properties of a substance to predict an unknown property, either of that substance or another one. We will find that sometimes we can do this and sometimes we can not. But what is the origin of these partial correlations?
§11.7 The solid <==> gas transitions: Compared with the phase transitions considered in §11.3 and §11.4 the solid ¤ gas transition is relatively understudied. We will find it is relatively easy to understand the process using a surprising extension of the cell model of a liquid.
§11.9 Other types of phase transitions: We mentioned in Chapter 10 that there is the concept of a phase transition could be applied more widely than to changes between solids in liquids and gas. In this section we look at what these transitions are and how they can be studied .