Introduction
A thermodynamic description of a process needs a well-defined system. A thermodynamic
system contains everything of thermodynamic interest for a particular chemical process within a boundary. The boundary is either a real or hypothetical enclosure or surface that confines the system and separates it from its surroundings.
In order to describe the thermodynamic behaviour of a physical system, the interaction between the system and its surroundings must be understood. Thermodynamic systems are thus classified into three main types according to the way they interact with the surroundings: isolated systems do not exchange energy or matter with their surroundings; closed systems exchange energy with the surroundings but not matter; and open systems exchange both energy and matter with their surroundings.