STANDARD QUANTITIES IN CHEMICAL THERMODYNAMICS - FUGACITIES, ACTIVITIES, AND EQUILIBRIUM-CONSTANTS FOR PURE AND MIXED PHASES (IUPAC RECOMMENDATIONS 1994)

The standard chemical potential mu is defined in terms of a specified state of aggregation, a specified temperature and a specified standard pressure. Other s thermodynamic quantities are obtained from mu by th e usual mathematical operations. In this report definitions are given for the standard chemical potential of a substance B in the following states of aggregation: gas phase whether pure or mixed, condensed phas e pure or mixed, solvent substance in solution, and solute substance i n solution. Fugacities and virial coefficients are introduced in the d iscussion of gases and activity, activity coefficients, and osmotic co efficients in the discussion of condensed phases. Expressions for the standard equilibrium constant are given for a reaction in the gas phas e, in a condensed phase and in a solution. Some numerical examples are given and relative magnitudes of various terms in the equations are i llustrated.