Introduction - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 12

The physical quantity amountofsubstance is of paramount importance to environ-
mental engineers. The SI unit for this quantity is the mole defined as the amount of
substance of a system that contains as many elementary entities as there are atoms in
0.012 kg of carbon-12. IUPAC recommends that we should refrain from calling it the
“number of moles.” Much of the published literature is based on the more familiar
CGS units. The relations between the common CGS and SI units for some important
derived quantities of interest in environmental engineering are given in Table 1.5.
A description of the most common units in environmental engineering is given
in Appendix 4 and the reader should familiarize himself or herself with these before
proceeding further.
1.6 STRUCTURE OF THE TOPIC
The topic is divided into six chapters. It can be broadly divided into two sections. The
first section (Chapters 2-4) is on chemical thermodynamics whereas the second sec-
tion (Chapters 5 and 6) is on chemical reaction kinetics. Chapter 2 is an introduction to
the thermodynamics of homogeneous phases composed of single or multiple species.
It also introduces the important concepts of free energy and chemical potential that
are of paramount importance in dealing with equilibrium systems in environmen-
tal engineering. A concise description of surface thermodynamics is also included in
Chapter 2. Chapter 3 is an extension of the thermodynamics of homogeneous systems
to heterogeneous and multicomponent systems. The important concepts of activity
and fugacity and nonideal solutions and gases are dealt within this chapter. Chapter 4
deals with the applications of the concepts developed in Chapters 2 and 3 on air-water,
soil-water, and air-soil equilibria to illustrate the concept of equilibrium partitioning
between compartments in environmental engineering. Applications of equilibrium
thermodynamics in waste treatment operations are also described. Chapter 5 gives a
short summary of the essential aspects of chemical reaction kinetics. Concepts such
as reaction rates and activation energies are introduced and discussed. The concepts
developed in Chapter 5 are used to illustrate the applications of chemical kinetics
in environmental waste treatment processes and biological systems in Chapter 6.
Applications of reactor models and transport theory are exemplified in Chapter 6.
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