Redox chemistry measurement

We have already seen from Faraday s laws how a zero current implies that no redox chemistry occurs. Accordingly, we stipulate that the meter must draw absolutely no current if we want to measure the battery s emf at equilibrium. Henceforth, we will assume that all values of emf were determined at zero current. 

To learn that analytical measurements involving concentration change (in response to redox chemistry) are termed dynamic. 

The redox chemistry of [NbO(TPP)(MeCOO)] was investigated by means of cyclic voltammetry and controlled potential electrolysis the reduction of Nbv to NbUI was found to occur prior to the reduction of the ligand. The redox potentials were measured for the [Nbv0(TPP)(MeC00)]/[NbIV0(TPP)l/[Nbm(TPP)]+/[NbI (TPP)] systems and found to be -0.94, 1.1 and -1.48 V respectively.334... 

The redox chemistry of PQQ has been investigated by a number of research groups. Duine et al. [14,15] performed potentiometric titrations of PQQH2 at several pHs and measured the redox potential of PQQ/PQQH2. Eckert et al. [16,17] compared the redox properties of PQQ with those of o-phenanthroline quinones. Kano et al. [18] performed cyclic voltammetry at acidic pH. Bergethon [19] investigated the amperometric detection of PQQ as a tool for HPLC. From pulse radiolysis experiments, McWhirter and Klapper [20] derived a value of -122 mV (NHE) for Em PQQ/PQQH at pH 7, as compared to the value of - 218 mV calculated from mediator-linked potentiometric titrations [15],... 

Measures, C.I., McDuff R.E. and Edmond, J.M. (1980) Selenium redox chemistry at GEOSECS I re-occupation. Earth Planet. Sci. Letts, 49, 102-108. 

Supramolecules 63-65 were designed to exploit the well-known redox chemistry of electronically excited [Ru(bpy)3] +-type complexes with nitroaromatics [164]. For both systems (R = H and Me), the excited-state lifetime of the Ru(II) polypyridyl donor is sufficiently long that concentration-dependent and -independent kinetics were observed. The concentration-dependent rate arises from the bimo-lecular electron transfer reaction between uncomplexed Ru(II) polypyridyl donor and the 3,5-DNB acceptor. The measured bimolecular rate constants were in ac-... 

Porphyrins are ideal for investigations of light-induced charge separation and oxygen transport in vesicular solutions. Their intense Soret band at 400 nm allows measurement at concentrations down to 10 M their fluorescence spectra being detectable even at 10 M. Photo- and redox chemistries are extremely variable depending on the central metal ion and substituents. ... 

When the overall oxidation state of a system is desired, unless a water is obviously anaerobic (e.g., it has an H2S odor) one should first attempt to measure dissolved oxygen as an index of system redox state. Eh measurements are unlikely to be stable and thermodynamically meaningful in surface-waters, except in acid waters (where ferrous and ferric species are usually present). Eh measurements may be stable and meaningful in anaerobic sediments or groundwaters, when species of iron, sulfur, and manganese dominate the redox chemistry, but otherwise are of qualitative value only. 

Early studies of electrochemically prepared PAn films used cyclic voltammetric techniques for the characterization of their electrochemical properties [16,145], Most of these studies addressed the chemical revesi-bility of the redox chemistry of the PAn films thus prepared and various forms of PAn were proposed to be involved in these redox chemistries [145], Depending on the oxidation state and whether or not it is protonatcd, PAn can be either an insulator or a conductor. The conductivities were measured in the dry state with mostly a four-probe method. Also, the molecular weight of electrochemically prepared PAn was found to be approximately 80000 [145b],... 

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