Activities and Activity Coefficients

Abstract

At equilibrium, the species activities are such that the following relationship is satisfied: K • = a M m eq · a N n eq a A a eq · a B b eq. (3.2) K • is the thermodynamic equilibrium constant. Its numerical value depends only on the temperature and on the conventions chosen to define activities (for condensed phases, it depends very little on the system pressure). Equation (3.2) expresses the mass law. As already demonstrated in Chap. 2, it results from thermodynamic considerations.