Entropy in Classical Thermodynamics: The Importance of Reversibility

Abstract

The concept of entropy is introduced within the context of classical thermodynamics where it was first developed to answer the questions: What happens when heat spontaneously goes from hot bodies to cold ones? To figure out this change, the transfer process must have some peculiar features that make it reversible. First of all, to be studied, systems and processes must be conceptualised as occurring at equilibrium conditions, or in conditions close to equilibrium. A first description of equilibrium is provided.

Keywords: Balancing of forces, Classical thermodynamics, Clausius’ equation, Dynamic equilibrium, Entropy, Equilibrium conditions, Friction, Heat capacity, Heat dissipation, Ideal gas, Infinitesimal change, Irreversible process, Isothermal process, Potentially available energy, Quasi-static process, Reversible process, Stationary state, Thermal energy, Transfer of heat, Turbulence.