CHAP. 1: BASIC TERMS [CONTENTS] 24
Chapter 1
Basic terms
A good definition of basic terms is an essential prerequisite for the study of any
physicochemical processes. Some of these terms may be also used beyond the field of
physical chemistry, but their meaning is often slightly different. In this chapter we will therefore
sum up the major basic terms that will be used in the subsequent parts of this book.
1.1 Thermodynamic system
The concept (thermodynamic)systemas used in this book refers to that part of the world
whose thermodynamic properties are the subject of our interest, while the termsurroundings
is used for the remaining part of the universe.
Note:Both a certain part of the real space and a certain part of the imaginary (abstract)
space forming a simplified model system, e.g. an ideal gas, may be chosen as a system.Systems are classified as isolated, closed and open, based on their inter-relations with their
surroundings.
1.1.1 Isolated system
A chemical system exchanging neither matter nor energy with its surroundings is anisolated
system.