Quantum mechanics provides the information about the energy states or levels of a molecular system while the statistical mechanics gives the possible arrangements of the molecules in various energy states or levels. Therefore, study of statistical thermodynamics presumes not only classical thermodynamics but also quantum mechanics and calculus (differential and integral)
Actually, thermodynamics is an experimental science which is concerned with the bulk or macroscopic properties of a system of interest without making any reference to the contributions of individual constituent, molecule, ion or atom. Statistical mechanics aims to derive the bulk (observable) properties of mater using the laws of mechanics applied on the constituent particles. However in statistical thermodynamics we deal with system which changes with time in the direction to equilibrium state. The purpose of statistical thermodynamics is to understand the behavior of the large assemblies of (relatively) simple systems such as molecules in a gas, atoms in crystal in terms of the behavior of its constituents.
In the first section we will introduces the three types of statistics and the basic differences between classical thermodynamics & statistical thermodynamics. In the next sections we will discuss about ensembles, microstates & macrostates, thermodynamic probability and distribution of particles which will help us to describe the behavior of a system of large number of particles elegantly. Then you will learn to establish a relationship between entropy and thermodynamic probability which bridges the thermodynamics and statistical view-point. In the next section, we will derive the Boltzmann distribution law for the equilibrium state (i.e., most probable distribution). This introduces a very important parameter known as Partition Function, f. Then we will derive few thermodynamic parameters in terms of f. You will learn to derive the partition function for few simple systems in the subsequent pages.
- Lecturer : Ikechukwu Kingsley Ijoma