Equilibrium, disequilibrium and the steady state; properties of pure gases; the fundamental relationships; phase equilibria in simple systems; thermodynamics of solutions; calculation of activities in gas mixtures, minerals and silicate melts; electrolyte theory; mineral equilibria I - the equilibrium constant; mineral equilibria II - chemical potential diagrams; mineral equilibria III - oxidation-reduction reactions; thermodynamic data - measurements and estimations; thermodynamic data - compilation and evaluation; geochemical modelling. Appendices: units, symbols and fundamental constants; exact differentials and partial differentiation; derivation of activity relationships for ideal mixing of ions on crystallographic sites; thermodynamic data for selected aqueous species, minerals and reactions at 25c, 1 bar; sources of thermodynamic data.