The Notion of Activity in Chemistry

1st part: The Activity in Classical Thermodynamics.- Thermodynamic systems.- Gibbs and Helmhotz energies.- Escaping tendency and molar Gibbs energy.- Partial molar properties.- Chemical potential or partial molar Gibbs energy.- An overview of the notion of activity.- The concept of fugacity.- Ideal solutions.- Definitions of the activity.- Activity of a gaz.- Activities of non- electrolytes in solutions.- Activities of electrolytes: definitions.- Determination of the activity of non-electrolytes.- Determination of the activity of electrolytes.- Debye and Hückel 's relations.- Excess Gibbs energies and activities.- Chemical equilibrium constants : activities and Gibbs energies of reactions.- Derivation of thermodynamic equilibrium constants- pH and its measure.- General principles of calculations of ionic species concentrations in solutions involving activities .- 2nd part: The Activity in Statistical Thermodynamics.- Statistical thermodynamics in brief.- Concept of ensembles and postulates.- The canonical ensemble: notion of distribution.- Thermodynamic quantities in the framework of the canonical ensemble.- Other ensembles .- Systems of molecules and subsystems independent distinguishable and "indistinguishable".- Perfect gases.- Classical statistical mechanics- Notion of configuration - Classical canonical partition function.- The configurational partition function - Molecular distribution functions.- The radial distribution function.- Radial distribution function and thermodynamic quantities- calculations of the internal energy and of the pressure of a system.- Radial distribution function and calculation of the isothermal compressibility coefficient of a system.- The chemical potential and the radial distribution function: General formal introduction of the activity and of the activity coefficient.- Imperfect gases - The virial coefficients in terms of interaction potential energies.- A statistical expression of the activity: A relation between it and the concentration in the case of an imperfect gaz.- Activities of gases in a mixture of imperfect gases.- Chemical equilibria between gases and statistical thermodynamics.- Activity coefficients of gases.- Activities and concentrations of non-electrolytes in dilute liquid solutions - McMillan- Mayer's theory of their osmotic pressure.- A study of dilute solutions of non-electrolytes at constant pressure and temperature.- The activity coefficients of solutes in binary non-electrolyte solutions.- Molecular distribution functions in binary mixtures.- The Kirkwood-Buff's theory- Changes of chemical potentials of solutes with their concentrations at constant pressure and temperature.- Expressions of the chemical potentials of the components of ideal solutions of non-electrolytes.