Effective activation energy

Anhydrous NaC102 crystallizes from aqueous solutions above 37.4° but below this temperature the trihydrate is obtained. The commercial product contains about 80% NaC102. The anhydrous salt forms colourless deliquescent crystals which decompose when heated to 175-200° the reaction is predominantly a disproportionation to C103 and Cl but about 5% of molecular O2 is also released (based on the C102 consumed). Neutral and alkaline aqueous solutions of NaC102 are stable at room temperature (despite their thermodynamic instability towards disproportionation as evidenced by the reduction potentials on p. 854). This is a kinetic activation-energy effect and, when the solutions are heated near to boiling, slow disproportionation occurs ... 

It must be emphasised in this context that changing T also changes D and that whereas both kp+ and k will be reduced by the normal activation energy effect, the concurrent increase in D will also decrease kp+ but will increase k, thus counteracting the thermal deceleration of the ion-pair propagation. It was the need to explain Arrhenius plots which have a minimum and kinked Arrhenius plots of DP (for isobutylene in CH2C12, TiCl4, H20) [16] that produced the first detailed treatment of the temperature-dependence of the rate and DP in terms of a dieidic polymerisation by paired and unpaired cations. 

The authors reported that employing DMB instead of benzene increases the activation energy, effectively lowering the rate of the reaction. This is in agreement... 

Possible excited state reaction schemes are suggested to account for emission lifetimes and their apparent activation energies, effects of added anions (OH , CN , COs ) on emission, and final products in photoaquation of [Rh(NH3)5Cl] (Cr only lost) and [Rh(NH3)sBr] (both Br and NH3 lost). Photoaquation rates for bromide loss are much greater for cis-and trans-[Rh(NH3)4Br2] than for [Rh(NH3)sBr]. Ammonia loss is also much faster from the c/s-dibromo complex than from [Rh(NH3)sBr]. Combination of new measurements on emission lifetimes with published data on quantum yields permits the estimation of reaction rate constants... 

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