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separated and contact ion pairs, and possibly a solvent separated dimer (the solvent separated ion pair and dimer are spectroscopically indistinguishable as explained above). Microwave spectra which reflect differences in moments of inertia of dipolar species are particularly sensitive to the presence of apolar species, and in fact the present results suggest the existence of dimers at concentrations above 0.1 mol dm-3. The relaxation spectra analyzed above confirm the existence of both contact and solvent separated ion pairs and indirectly confirm the
Salomon et al. existence of contact dimers. An order of magnitude value for Kq can be extracted from the microwave spectral data. Acknowledgment. This work was supported by the Army Office for Scientific Research, Durham, N C under Grant No. DAAG29-85-KO051. The authors express their gratitude for generous support. Registry No. LiAsF,, 29935-35- 1; LiCI04, 7791-03-9; MeOAc, 7920-9.
COMMENTS Reply to Comments on “The Kinetic Mass Action Law Revisited by Thermodynamics” Sir: In a Comment’ by Garcia-Colin about our paper,* two arguments were developed. First, it was claimed, quoting ref 1, that ”the statement that the kinetic mass action law (KMAL) can be derived by appealing to a minimum number of assumptions, implying by this that those used are only of thermodynamic nature, is untenable”. Second, it is argued by Garcia-Colin that, still quoting him, “the derivation proposed in ref 2, is at best equivalent to the standard one given in several well-known monographs on the s ~ b j e c t ’ ’ . ~We , ~ show briefly in this reply that neither of these two arguments is well founded. 1. We never have asserted that KMAL can be derived by using exclusively thermodynamic arguments. Anyone working in thermodynamics is fully aware that the complete knowledge of a constitutive equation requires in addition experimental observations and complementary information from other theories, such as statistical mechanics and quantum mechanics. This was furthermore explicitly written in ref 2 at the end of section 3. It is also claimed by Garcia-Colin that expression 3.17 in ref 2 cannot be considered as the kinetic mass action law since it ( I ) Garcia-Colin, L. J . Phys. Chem. 1988, 92, 3017. (2) Lebon, G.; Torrisi, M.; Valenti, A. J . Phys. Chem. 1987, 91, 5103. ( 3 ) de Groot, S. R.; Mazur, P. ”+equilibrium Thermodynamics; Dover: New York, 1984; Chapter IO. (4) Haase, R. Thermodynamics of Irreversible Processes; Addison- Wesley: Reading, M A , 197 I ; Chapter 2.
cannot be shown that w(T,p,$)is equal to the quantity kpr(@Ja)”a. As stated above, it is clear that we cannot establish such a result. We need for that what Garcia-Colin calls a mechanistic assumption, but it is worth noticing that the coefficient w ( T,p,s) is perfectly compatible with an expression like Garcia-Colin’s eq 8 in ref I . Moreover, and this is shown in section 4 of the Lebon et al. paper,* the only property that is provided by thermodynamics concerns the sign of w . 2. The second criticism mentioned by Garcia-Colin is that “the results of ref 2 are at best equivalent to those already given in the l i t e r a t ~ r e ” . The ~ , ~ latter references concern the classical theory of irreversible thermodynamics which predicts a linear relation between the rate of advancement of the reaction E and the affinity A. As stated explicitly in ref 3 and 4, such a result is only valid in the close vicinity of equilibrium. In ref 2 , we have obtained a result that is valid in the nonlinear regime, Le., far from equilibrium. Institute of Physics LiPge University B 4000 LiPge, Belgium
G . Lebon*
Dipartimento di Matematica Uniuersita di Catania Catania, Italy
M. Torrisi A. Valenti
Receiced: January 9, 1989; In Final Form: January 31, 1989
