Numerical Entropy
Harvey S. Leff · 2020
The entropy of any object, element, or compound approaches zero or a positive number as the lowest possible temperature, absolute zero, is approached. At any subsequent temperature, the corresponding entropy depends upon how much energy was added to the material, and how much of that energy is stored within it. This illustrates a close connection between energy and entropy. Unfortunately, entropy discussions are commonly divorced from reality, ignoring both the numerical entropy and the close linkage between energy and entropy. Entropy is a measurable thermodynamic state function, i.e., it is a function of the equilibrium state of a thermodynamic system. This chapter discusses the nuances of entropy by using the Nernst theorem. Various mathematical models for gases and solids exist and these can be studied to see if common forms of the third law of thermodynamics hold for them. The chapter lists some such models and their results.