Volume 3, Issue 1, 1985
25th September, 2022
Termodynamic Properties of Polar and Non-Polar Solutes in Aqueous Solution
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by Sergio Cabani
5-20
DOI: doi:10.4152/pea.198501005
Estudo Comparativo da Electrocristalização do SnS em Eléctrodos de Amálgama e Estanho Sólido
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by M. I. S. Pereira, M. F. G. Silva, M. J. B. V. Melo et al.
21-34
DOI: doi:10.4152/pea.198501021
A comparative study of the electrodeposition of tin (II) sulphide on tin and tin amalgam, has been done in bicarbonate solutions using a potentiodynamic technique. The influence of sweep rate and sulphide concentration, on the peak -current has been studied.
The results show, that in the early stages, the deposition takes place by a different mechanism in each substrate. However the thickning of the film seems to occur by diffusion through the solid phase, in both substrates, for high sulphide concentrations, while for low concentrations the rate-determining step is the diffusion in solution.
Probing the Selectivity of Electro-generated Transition-Metal Sites
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by T. I .Al-Salih, C. J. Pickett, R. L. Richards et al.
35-39
DOI: doi:10.4152/pea.198501035
The formation of complexes [M0L2(dppe)^], [MoL^Cdppe)^] and [MoLL'(dppe^] (L=CNBut, L'=C0) (by imposing a cathodic clamp beyond the reduction peak of [MoC^idppe^] in the presence of L and L') was monitored by ramp-clamp reverse ramp voltammetry and, from the analysis of the product distribution, it was concluded that the unsaturated centres of the types {Moidppe^}, {MoLCdppe)^} and {MoL' (dppe^} discriminate (although equally) between the two substrates, the addition of CO at each site occurring 2.3 times as fast as the addition of CNBu*" to the corresponding site.
Ligand and Structural Effects on the Redox Potential of Octahedral 18-Eleetron Complexes with 14-Electron or 12-Electron Metal Centers
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by A J. L. Pombeiro
41-65
DOI: doi:10.4152/pea.198501041
Electrochemical P ligand and E (electron-richness) and S (8) 3 (polarisability) metal site parameters, defined by other authors for octahedral 18-electron complexes with 16-electron square pyramidmetal centres, are extended to octahedral 18-electron compounds of the types [*1 L ] with 14-electron (n = 2) or facial 12-electron (n = 3) metal sites, by defining new overall P^^ ligand parameters as, e.g.,PnL-E1/2[Cr(CO)6-nLJ " E1/2[Cr, {cis-M(C0)4> (M = Cr, Mo, W) and {fac-M(CO)^ } (M = Cr, Mo) binding metal centres, and the corresponding ligand P^L and metal site (Es,B) parameters are estimated. For the c_is_- 14-electron metal sites (n = 2), bidentate chelating ligands (LL) are also considered.
An Electroanalytical Technique for the Determination of Total Iron in Nutrient Solutions
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by W. J. Albery, Maria M. P. M. Neto
67-79
DOI: doi:10.4152/pea.198501067
A new on line technique, the packed bed wall-jet electrode, for the determination of total iron in hydroponic solutions has been developed. To avoid interference from 0- and to convert Fe(III) to Fe(II) a packed bed electrode is inserted upstream of a wall-jet electrode. The total iron is then determined by the oxidation of Fe(II) on the downstream electrode. The bed is shown to remove 99% of the 02 present
in air saturated solutions, thereby removing the necessity for deoxygenating the test solution by bubbling N2. Linear calibration plots have been obtained for iron concentrations from 0.050 to 1.5 mmol dm and the technique has been tested in samples of nutrient film solution.
