Introduction and Definition of Terms
Thermodynamics is the physical science that focuses on the relationship between energy and work as well as the equilibrium states and variables of systems that are being investigated. A central aim of applied thermodynamics is the determination of the effect of the surroundings on the equilibrium state of a given system. Thermodynamic state variables are either extensive or intensive. Of the several ways to graphically represent the equilibrium states of the existence of a system, the constitution or equilibrium phase diagram is the most popular and convenient. Thermodynamics is summarized by stating its laws, which can be treated either as experimentally determined facts of nature or as axioms from which other thermodynamic relationships can be derived. Zeroth Law introduces the important intensive thermodynamic variable temperature, T, which is a measure of the thermal intensity of a material and allows the determination of thermal equilibrium.