Like all sciences,
thermodynamics is based on principles and laws formulated using a precise
vocabulary. This allows concepts and definitions to be definitions without
ambiguity. Chapter I therefore presents the basic elements study thermodynamics
and solve practical problems. We begin the chapter with a general discussion of
thermodynamics. The system of units used in this book is also clarified. Next,
we define basic concepts system, control volume, thermodynamic variables,
thermodynamic equilibrium, evolutions and cycles. The notions of temperature
and temperature scales are introduced, then we determine the composition of gas
mixtures.