Kinetics of electrode processes of complexes in polarography. VII. Formation of the complex of cadmium ion with the ethylenediaminotetraacetic acid as a reaction deactivating the product of a rapid electrode reaction

1960 ◽  
Vol 25 (12) ◽  
pp. 3153-3158 ◽  
Author(s):  
J. Koryta ◽  
Z. Zábranský
Keyword(s):  
Electrode Reaction ◽  
Cadmium Ion ◽  
Electrode Processes ◽  
Kinetics Of

scholarly journals The kinetics of electrode reactions. I and II

1938 ◽  
Vol 169 (937) ◽  
pp. 206-234 ◽  
Keyword(s):  
Electrode Potential ◽  
Surface Reaction ◽  
Reference Electrode ◽  
Electrode Reaction ◽  
Potential Difference ◽  
Concentration Difference ◽  
Electrode Processes ◽  
Electrode Reactions ◽  
Concentration Changes ◽  
Kinetics Of

In any surface reaction taking place in a Solution, it is clear that the concentration of the reactants in the vicinity of the surface must fall. If the concentration in the bulk of the solution remains constant, a steady state may finally be reached, in which the rate of replenishment of the solution in this region, from the bulk, is equal to the rate at which the reactant in question is used up. But, in general, such a state is only attained when the concentration at the surface is less than that in the rest of the solution. If the reaction considered is an electrode reaction, these concentration changes may affect the electrode potential. This question is therefore of importance in the study of overpotential, and of the kinetics of electrode processes generally. The overpotential at an electrode is defined as the potential difference between this electrode and a similar unpolarized reversible electrode in the same solution. In practice this reference electrode is usually situated outside the region affected by the concentration changes near the electrode at which the reaction is taking place. The measured potential difference between the two electrodes, i.e. the measured overpotential, may therefore include a term due to the concentration difference.

Pressure effects and solvent dynamics in the electrochemical kinetics of the tris(hexafluoroacetylacetonato)ruthenium(III)/(II) couple in nonaqueous solvents

2001 ◽  
Vol 79 (5-6) ◽  
pp. 841-847 ◽  
Author(s):  
Jinkui Zhou ◽  
Thomas W Swaddle
Keyword(s):  
Free Energy ◽  
Activation Barrier ◽  
Electrode Reaction ◽  
Pressure Effects ◽  
Electrochemical Kinetics ◽  
Free Energy Barrier ◽  
Exchange Reactions ◽  
Electrode Processes ◽  
Solvent Dynamics ◽  
Kinetics Of

Rate constants and reactant diffusion coefficients for the Ru(hfac)30/– electrode reaction have been measured at 25°C as functions of pressure (0-200 MPa) in acetone, acetonitrile, methanol, and propylene carbonate. In sharp contrast to the negative volumes of activation ΔVex‡ found for the corresponding bimolecular self-exchange reaction in organic solvents, the volumes of activation ΔVel‡ for the electrode reaction are markedly positive, ranging from 8 to 12 cm3 mol–1. The volumes of activation ΔVdiff‡ for reactant diffusion (which can be equated to the volume of activation ΔVvisc‡ for viscous flow) range from 12 to 19 cm3 mol–1. For the Debye solvents acetonitrile and acetone at least, ΔVel‡ is given within the experimental uncertainty by ΔVdiff‡ + (ΔVex‡/2). In this relation, the numerical value of ΔVdiff‡ represents indirectly the dominant contribution of solvent dynamics (solvent friction) to ΔVel‡, and ΔVex‡/2 represents the pressure dependence of the free-energy barrier height for the electrode reaction. It is proposed that solvent friction is important in nonaqueous electrode processes but not in the corresponding bimolecular self-exchange reactions because the free-energy activation barrier is twice as high in the latter.Key words: electrode reaction kinetics, solvent dynamics, electron transfer mechanisms, pressure effects, volume of activation.

Volumes of activation for electrode processes of various charge-types in nonaqueous solvents

2001 ◽  
Vol 79 (12) ◽  
pp. 1864-1869 ◽  
Author(s):  
Mitsuru Matsumoto ◽  
Delanie Lamprecht ◽  
Michael R North ◽  
Thomas W Swaddle
Keyword(s):  
Electron Transfer ◽  
Reaction Rate ◽  
Electrode Reaction ◽  
State Theory ◽  
Exchange Reactions ◽  
Pt Electrode ◽  
Electrode Processes ◽  
Solvent Dynamics ◽  
The Mean ◽  
Dynamical Control

Volumes of activation (ΔV‡el) are reported for electron transfer at a Pt electrode of Mn(CN-cyclo-C6H11)62+/+ in acetonitrile, acetone, methanol, and propylene carbonate, and of Fe(phen)33+/2+ in acetonitrile. In all cases, ΔV‡el is markedly positive, whereas for the homogeneous self-exchange reactions of these couples in the same solvents the corresponding parameter is known to be strongly negative. The rate constants for the electrode reactions correlate loosely with the mean reactant diffusion coefficients (i.e., with solvent fluidity) and the ΔV‡el values with the volumes of activation for diffusion (i.e., for viscous flow), consistent with solvent dynamical control of the electrode reaction rate in organic solvents. A detailed analysis of ΔV‡el values of the kind presented for a couple with an uncharged member (Zhou and Swaddle, Can. J. Chem. 79, 841 (2001)) fails, however, either because of ion-pairing effects with these more highly charged couples or because of breakdown of transition-state theory in predicting the contribution of the activational barrier. Attempts to measure ΔV‡el for the oxidation of the uncharged molecule ferrocene at various electrodes in acetonitrile were unsuccessful, although ΔV‡el was again seen to be clearly positive.Key words: electrode kinetics, volumes of activation, nonaqueous electron transfer, solvent dynamics.

Kinetics of Electrode Processes of LiFePO4 in Saturated Lithium Nitrate Solution

2007 ◽  
Vol 23 (01) ◽  
pp. 129-133
Author(s):  
HUANG Ke-Long ◽  
◽  
◽  
YANG Sai ◽  
LIU Su-Qin ◽  
...  
Keyword(s):  
Nitrate Solution ◽  
Lithium Nitrate ◽  
Electrode Processes ◽  
Kinetics Of
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