Electrochemistry standard-state conditions

Other Coordination Complexes. Because carbonate and bicarbonate are commonly found under environmental conditions in water, and because carbonate complexes Pu readily in most oxidation states, Pu carbonato complexes have been studied extensively. The reduction potentials vs the standard hydrogen electrode of Pu(VI)/(V) shifts from 0.916 to 0.33 V and the Pu(IV)/(III) potential shifts from 1.48 to -0.50 V in 1 Tf carbonate. These shifts indicate strong carbonate complexation. Electrochemistry, reaction kinetics, and spectroscopy of plutonium carbonates in solution have been reviewed (113). The solubiUty of Pu(IV) in aqueous carbonate solutions has been measured, and the stabiUty constants of hydroxycarbonato complexes have been calculated (Fig. 6b) (90). 

Convection has long been coupled with electrochemistry, and the name hydro-dynamic voltammetry has become standard. In electroanalytical chemistry we mainly seek reproducible conditions. These are almost always attained by systems in which a steady convective state is achieved, although not always. Thus, the once popular dropping mercury electrode (see texts such as [74,257]) has convection around it, but is never in steady state it might be called a reproducible periodic dynamic state. 

Experiment has shown [140] that for standard conditions in solid-state electrochemistry (po2 = 1 atm, T = 673K) the corresponding standard absolute... 

Unlike the table of the Electrochemical Series, which lists standard potentials, values for radicals are experimental values with experimental conditions given in the second column. Since the measurements leadingtopotentialsforionradicalsare very dependent on conditions, an attempt to report standard potentials for radicals would serve no useful purpose. For the same reason, the potentials are also reported as experimental values, usually a half-wave potential (i i/2 in polarography) or a peak potential (Ep in cyclic voltammetry). Unless otherwise stated, the values are reported vs. SCE (saturated calomel electrode). To obtain a value vs. normal hydrogen electrode, 0.241 Vhastohe added to the SCE values. All the ion radicals chosen for inclusion in the tables result from electrochemically reversible reactions. More detailed data on ion radicals can be found mHaeEncyclopedia of Electrochemistry of Elements, (A. J. Bard, Ed.), Vol. XI and XII in particular, Marcel Dekker, New York, 1978. 

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