Nonideal systems, reactions activity coefficient

Independently of T, reaction 5.159 thus appears to proceed spontaneously toward the right, in agreement with the principle of Fe-F incompatibility in silicates, postulated long ago by Ramberg (1952). This fact also implies the nonideality of the system. According to Munoz (1984), the activity coefficients of OH-phlogopite and F-phlogopite in mixture are defined by... 

Experimental studies were carried out to derive correlations for mass transfer coefficients, reaction kinetics, liquid holdup, and pressure drop for the packing MULTIPAK (35). Suitable correlations for ROMBOPAK 6M are taken from Refs. 90 and 196. The nonideal thermodynamic behavior of the investigated multicomponent system was described by the NRTL model for activity coefficients concerning nonidealities caused by the dimerisation (see Ref. 72). 

Thus the correct rate expression (2.7.4) to use in nonideal systems is known. Its application is however quite difficult at the present time because it is hard to guess at the proper value of the activity coefficient of the transition state even when activity coefficients of reactants are available. In practice, it will be necessary, regrettably, to forget about nonideality except under rare circumstances. The penalty for this simplification might be a rate constant that is not constant but drifts as the extent of reaction increases. Recourse to incorrect expressions such as (2.7.11) should be avoided. 

Extension to a nonideal system Minimization of free energy Thermodynamics of reactions in solution Partial molar properties Medium and substituent effects on standard free energy change, equilibrium constant, and activity coefficient General considerations Solvent and solute operators Comments... 

---