## Energy and structure (CH2204)

### Aims

This module aims to develop a good understanding of the use of the three laws of thermodynamics. This will include calculations involving relationships between thermodynamic quantities. Applications to common problems in chemistry and electrochemistry will be emphasised, including corrosion, chemical analysis, chemical change and phase equilibria.

### General description

This module will develop the laws of thermodynamics and their use in quantitative calculations involving entropy, enthalpy and Gibbs free energy, including the relationships between equilibrium, free energy, chemical potential and activities. Applications of the laws to industrial processes and to the transformation between phases will be considered. The concept of microstates will be introduced and the Boltzmann relation between microstates and entropy will be discussed. The discussion of thermodynamics will be developed to consider solution properties and applications to electrochemical cells.

### Syllabus content

First, Second and Third laws of thermodynamics. Their use in quantitative calculations involving Entropy, Enthalpy and Gibbs free energy.

Brief introduction to the use of partial differentials

Changes in internal energy, Carnot cycles and heat engines.

Extensions of first year work to relationships between equilibrium, free energy and chemical potential (Clausius-Clapeyron equation, heat capacities Cv and Cp, adiabatic expansions, phase stability and Ellingham diagrams)

Solutions and solubility products

Boltzmann formula for entropy and configurational entropy

Electrochemical potentials - relationships to chemical potentials. Nernst Equation

Relationship between E and equilibrium constant. Concept of activity. Redox potentials. Links between Gibbs free energy and electrical work for reversible cells. Gibbs-Helmholtz equation and its application to electrochemical cells. Thermodynamic quantities such as DG, DH, DS, solubility products and susceptibility to corrosion from measurements of EMF. Ionic strength principle. Debye-Huckel limiting law.

#### Practical work :

Measurement of equilibrium constants using a spectroscopic method.

Measurement of Gibbs free energies, entropies and enthalpies for a reversible electrochemcial cell.

Meaurement of standard electrochemical potentials.

Verification of Debye-Huckel limiting law and measurement of solubility products, ionic activity coefficients and activities of ions.

Measurement of standard enthalpies of formation and reaction stoichiometries via calorimetry.

Spectroscopic determination of bond dissociation energies of iodine together with other thermodynamic quantities via a statistical approach.