Classical Thermodynamics

The science dealing with the basic concepts, the thermodynamic laws and their interrelationships is known as the classical thermodynamics. Chapter deals with the four laws of thermodynamics. The zeroeth law gives the concept of temperature. The First Law of thermodynamics concerned with the quantitative aspects of interconversion of energies explains internal energy, enthalpy, heat capacity, and heat of reaction/formation/combustion/transformation/solution. The concentrated efforts of many scientists in the nineteenth century to apply the first law of thermodynamics to the calculation of maximum work obtained from a perfect engine and prediction of feasibility of a reaction in a desired direction led to the development of the second law of thermodynamics which has had a far reaching influence on the subsequent development of science and technology. This law introduces the concept of entropy. The third law of thermodynamics states that that the entropy of a pure crystalline substance approaches zero as the temperature approaches absolute zero. The concept of Gibbs free energy has been developed to explain the feasibility of a reaction. The usefulness of the van’t Hoff isochore in the calculation of Gibbs free energy change of a reaction under varying concentration and pressure of the system has been explained with aid of a technical example, silicothermic reduction of MgO (Pidgeon process). It has been demonstrated that the qualitative conclusion based on the Le Chatelier principle can be calculated quantitatively by the van’t Hoff equation. The Clausius–Clapeyron equation extremely useful in calculating the effects of temperature and pressure changes on the melting point of solids, boiling point of liquids, and any solid-solid phase transformations has been derived. The application of the phase rule has been discussed in single component system, binary eutectic alloys, reduction, decomposition and dehydration as well as in roasting of sulfides.