Reaction Moments from Dielectric Data

The chemical reaction moment AM refers to that part of the total moment M which changes in the course of a chemical-conformational transition. Differentiation of Eq. (3.2) with respect to the reaction variable results in 

Equation (3.4) may be called the continuum expression for the chemical reaction moment at constant total volume between the capacitor plates, usually realized at low field intensities and diluted solutions of the reaction partners. When volume changes occur electrostriction terms must be explicitly considered.  

Under isothermal-isobaric-isochoric conditions, M is solely a function of and E. The dependence on E at constant defines a (normal) physical part whereas the dependence of M on at constant E may be referred to as the chemical contribution to a change in M. The field dependence of the total moment may then be expressed as 

At equilibrium in the presence of E the characteristic (dielectro-)chemical affinity A of dipole systems is zero and dA=Q. Hence the term (5iJ/5E)2 j=o can be calculated from Eq. (3.57) of part I we obtain 

At equilibrium there is no further change of M in the field E. Therefore dM/dE)y2=o is a constant at a given field strength. 

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