Migration of ions

Each ion has its own characteristic mobiUty. The total conductivity of the electrolyte is the sum of the conductivities of the positive and negative ions. This is known as Kohlrausch s Law of Independent Migration of Ions. 

Wandenings-geschwindigkeit, /. migration velocity. -sinn, m. direction of migration (of ions), -zahl,/. transport number. 

Semiconducting devices, switches and miniaturised v.h.f. circuits are all particularly sensitive to the slightest reaction on critical surfaces, and in devices calling for the highest levels of reliability even the most inert of the phenolic, epoxide and silicone resins are not considered to be fully acceptablecorrosion of electronic assemblies may often be enhanced by migration of ions to sensitive areas under applied potentials, and by local heating effects associated with current flows. 

Migration of Ions movement of ions towards the anode or cathode under an electric field. 

The viscosity of pure H2SO4 at 25°C is 27.6 times greater than that of water consequently the normal migration of ions is extremely slow. The comparatively high mobility of the (IISO4)- ion undoubtedly arises from successive proton transfers to the ion from an adjacent solvent molecule 2... 

For strong electrolytes the molar conductivity increases as the dilution is increased, but it appears to approach a limiting value known as the molar conductivity at infinite dilution. The quantity A00 can be determined by graphical extrapolation for dilute solutions of strong electrolytes. For weak electrolytes the extrapolation method cannot be used for the determination of Ax but it may be calculated from the molar conductivities at infinite dilution of the respective ions, use being made of the Law of Independent Migration of Ions . At infinite dilution the ions are independent of each other, and each contributes its part of the total conductivity, thus ... 

The term electrolyte is also used to denote a medium, such as a liquid solution or a porous solid, that can conduct electricity by the migration of ions. 

In the theoretical treatment of ion exchange polymers the roles of charge propagation and of migration of ions were further studied by digital simulation. Another example of proven 3-dimensional redox catalysis of the oxidation of Ks[Fe(CN)5] at a ruthenium modified polyvinylpyridine coated electrode was reported... 

One reason soils form is because of the endless migration of ions, molecules, and particles into the soil from meteoric inputs. Examples of meteoric inputs include H2O, CO2, O2, nitrogenous compounds, pollutants, salts, and dust. These molecules and compounds come from space, from the atmosphere and the oceans, and from other terrestrial systems. 

By definition the partial current density ij is the number of charges that in unit time cross the unit cross-sectional area due to the migration of ions j that is,... 

The second method, namely the moving boundary method, is based on the direct observation of migration of ions under the influence of an applied potential - unlike Hittorf s method in which the changes in concentration at the electrodes are measured. 

The way of preventing the Cu2+ ions formed at the cathode from diffusing over to the zinc anode is to interpose a barrier, and this can be achieved in two ways (i) a porous partition and (ii) a porous pot. The barrier permits migration of ions while the cell is in use, but minimizes the random diffusion of ions that otherwise takes place when the cell is not... 

A change in potential can cause any of several effects, including migration of ions into or out of the thin layer, adsorption, desorption, and faradaic reactions consuming or producing species adsorbed on the surface or in solution. For these reasons a difference spectrum (see Eq. (1.3) can exhibit both negative bands due to species formed and positive bands due to species consumed at the sample potential. 

The task of a cell separator is to impede a direct mixing of anolyte and catholyte and to decrease diffusion, but at the same time the migration of ions has to be possible without a too high voltage drop. Naturally, a compromise of these requirements has to be found. 

With the study of the migration of hydrogenium ions (H ) in a phenolphthalein gel by Lodge in 1886 and the description of the migration of ions in saline solutions by Kohlraush in 1897, a basis was set for the development of a new separation technique that we know today as electrophoresis. Indeed, several authors applied the concepts introduced by Lodge and Kohlraush in their methods and when Arne Tiselius reported the separation of different serum proteins in 1937, the approach called electrophoresis was recognized as a potential analytical technique. Tiselius received the Nobel Prize in Chemistry for the introduction of the method called moving boundary electrophoresis. ... 

Migration of Ions (especially sodliam) Into unprotected semiconductors results In the degradation of Junction characteristics such as reverse bias leakage currents so that the chip no longer performs to specifications and eventually falls. 

Smee, B.W. 1983. Laboratory and field evidence in support of electrogeochemically enhanced migration of ions through glaciolacustrine sediment. Journal of Geochemical Exploration, 19, 277-304. 

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