## 3 Discussion  
When AOT RM solutions of \(\rm[Co(NH_{3})_{5}OH_{2}]^{3+}\) and \(\rm[Fe(CN)_{6}]^{4-}\) are mixed, the precipitation of Co (II) hexacyanoferrate (II) occurs. When EDTA is added, soluble EDTA complexes of Co (II) are formed as soon as Co (II) is produced. So, EDTA is added to the reaction mixture to prevent the formation of the precipitate. In such a case, the electron transfer takes place, resulting in the ion pair of \(\rm[Co(NH_{3})_{5}OH_{2}]^{2+}/[Fe(CN)_{6}]^{3-}\). Linear plots of the inverse of \(\rm k_{obs}\) versus the inverse of the concentrations of hexacyanoferrite (III) ions give the ion-pairing constant (\(\rm K_{IP}\)) and the electron transfer rate constant (\(\rm k_{et}\)). Table 1 shows the \(\rm k_{et}\) and \(\rm K_{IP}\) values for the reaction between \(\rm[Co(NH_{3})_{5}OH_{2}]^{3+}\) and \(\rm[Fe(CN)_{6}]^{4-}\). It can be observed in Table 1 that the electron transfer rates become faster in smaller reverse micelles, and the ion-pairing constant is more significant for larger RMs. The faster electron transfer rate in smaller RMs can be rationalized based on the solvent reorganization energy and dielectric constant. According to the [PERSON] theory, the outer sphere electron transfer rates increase with decreasing solvent reorganization energies. The equations for the [PERSON] theory are as follows [23]  
\[\rm\Delta G^{*}=\lambda_{i}+\lambda_{o}+\rm\Delta G_{o} \tag{4}\]  
\[\rm k_{et}=Ze(-\rm\Delta G^{*}/R) \tag{5}\]  
where \(\rm\Delta G^{*}\) is the activation free energy, \(\rm\lambda_{i}\) and \(\rm\lambda_{o}\) are the inner and outer sphere solvent reorganization energies, respectively. \(\rm Z\) is the collision frequency, \(\rm e\) is the charge on the electron, \(\rm R\) is the universal gas constant, and \(\rm T\) is the temperature. The inner sphere reorganization energy (\(\rm\lambda_{i}\)) is assumed to be the same in the aqueous and RMs system:  
\[\rm\Delta\lambda_{(aq/RMs)}=0 \tag{6}\]  
Thus, the electron transfer rate constant (\(\rm k_{et}\)) is related to the solvent reorganization energy. Solvent reorganization energy increases with the increase in solvent (water) volume inside RMs; therefore, the electron transfer rate decreases with increasing RMs size. The research of [PERSON] and [PERSON] has supported this result [11]. They found a higher rate of electron self-exchange rate (\(\rm k_{ex}\)) in smaller RMs. This result can also be discussed in terms of ionic strength variation with the change in the size of reverse micelles. As previously determined, the ionic strength increases as RMs size decreases. [PERSON] et al. clearly showed the effect of ionic strength (\(\rm\upmu\)) on the electron transfer rate [24]. They showed that the electron transfer rate increases with the increase in ionic strength. Thus, the rate of electron transfer increases as the RMs size decreases. This result can be rationalized in the RMs of dielectric constant variation with the change in the size of reverse micelles. It has already been discussed in relation to electron transfer in nonaqueous solvents that electron transfer rate increases with the decrease \begin{table}
\begin{tabular}{|c|c|c|c|} \hline
**Entry** & \(\bf W_{o}\) & \(\bf k_{et}\) (\(\bf s^{-1}\)) & \(\bf K_{IP}\) \\ \hline
1. & aqueous & 6.88 \(\pm\) 0.20 & 100 \\ \hline
2. & 30 & \([6.94\pm 0.20]\times 10^{-4}\) & 6550 \\ \hline
3. & 20 & \([1.06\pm 0.41]\times 10^{-3}\) & 6450 \\ \hline
4. & 15 & \([1.18\pm 0.35]\times 10^{-3}\) & 6400 \\ \hline
5. & 10 & \([2.43\pm 0.41]\times 10^{-3}\) & 4500 \\ \hline \end{tabular}
\end{table} 
Table 1: Rate constants and ion-pairing constant at different RMs size. in dielectric constant. [PERSON] reported that the dielectric constant decreases with the decrease in the size of RMs [25]. He measured the effective dielectric constant in reverse micelles of n-heptane/AOT/water. [PERSON] studied the correlation of electron transfer rate in photosynthetic reaction centers with intraprotein dielectric properties [26].