Observable Properties

Abstract

In this chapter emphasis is deliberately put on the empirical aspects of thermodynamics. How can one measure the variables introduced in the previous chapters? What are the auxiliary properties that have to be defined in the whole range of relevant physical conditions? Without any claim to comprehensiveness, we will describe some of the main methods used to measure thermodynamic properties. Of course, an important point concerns the precision with which a property is known. Hence, we will give rough estimates of experimental uncertainties and indicate briefly under which conditions measurements can be made. Additional relations between state variables will also be derived. We will then discuss the case of adiabatic processes, introduce the important concepts of “absolute” and residual entropies with reference to Nernst’s law and conclude with a presentation of formation properties.