ABSTRACT
In this chapter we consider a number of aspects of chemically reacting systems
at both equilibrium and as they approach equilibrium. Th e role of the equilib-
rium constant and how it is aff ected by temperature is discussed. Examples of
enthalpy of reactions are given. A discussion for reacting systems not in equilib-
rium is provided, as well as a number of examples to illustrate the calculation
of the variation of substance concentration with time. We also consider briefl y
the language and purpose of irreversible thermodynamics (Kjelstrup and
Bedeaux 2010; de Groot and Mazur 1984) and electrolyte solutions (Robinson
and Stokes 2002) although in both cases our treatment is not intended to pro-
vide more than an opportunity to refer to the substantive literature on the top-
ics that interested readers may wish to consult.
