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Les volumes molaires apparents, ϕv, des sels R4NX, où R est un groupe alcoole et X un ion halogénure, ont été mesurés dans l'eau à 25°C. A partir de ces données, une nouvelle méthode est proposée pour la détermination des volumes molaires partiels individuels des ions; les rayons apparents des ions d'ammonium quaternaire en solution sont obtenus et comparés avec les valeurs trouvées par d'autres méthodes. On suppose que la dépendance de ϕv sur la molarité c est donnée par ϕv = ϕv0 + 1.868c2 + hc. La valeur négative du paramètre h est interprétée qualitativement.
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The significance of observations of rates of E.M.F.-decay on open-circuit at the nickel oxide electrode is examined in terms of the potential dependence of the surface capacitance associated with the processes occurring during decay. Determinations of volumes of oxygen evolved from the electrode during open-circuit E.M.F.-decay allow quantitative comparisons to be made between true Tafel slopes and open-circuit E.M.F. decay slopes. These slopes are shown to be identical only when the volume of oxygen evolved from the surface is a linear function of E.M.F. When the E.M.F. is a logarithmic function of the oxygen evolved, Tafel and decay slopes are …
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Previous electrostatic theories of salting-out of non-electrolytes by small ions give values of relative salting-out which are much lower (sometimes by a factor of 5) than those found experimentally. The distribution theories have therefore been examined and the following new modifications made: (i) A full exponential distribution function is used and not an approximate linear one. (ii) Dielectric saturation near the ions is allowed for. (iii) The Debye-Huckel field rather than ze/r^2 (the simple ionic field) is used to calculate the polarisation energy of the solvent and non-electrolyte. Modifications (i) and (ii) lead to values of relative salting-out which are …
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On open circuit in aqueous alkaline solutions the isolated nickel oxide electrode loses a significant fraction of its charge and evolves oxygen. The kinetics of self-discharge have been studied by measurements of the decay of E. M. F. and of rates of oxygen evolution. The self-discharge proceeds by local action at a rate determined by the rate of evolution of oxygen at anodic sites. Several reaction pathways are suggested and a probable mechanism is deduced by reference to the experimental kinetic behaviour.
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The overall electrolytic hydrogen evolution reaction 2 H3O+ + 2 e -> H2 + 2 H2O can proceed by several possible rate determining steps. Methods for distinguishing these at a given metal under various experimental conditions are discussed and the relationship between exchange currents for the reaction at various groups of metals and the heat of absorption of H at these metals is examined. Metals at which an absorbed H atom is formed in the rate determining step fall in a series where the exchange currents appear to increase with increasing heat of absorption of H at the metal, whereas …
