La crisis de desocupación en la Argentina (1993-1998)

En este documento de trabajo se presentan los primeros resultados de la investigación acerca de la denominada "crisis de la desocupación" que se desarrolla en la Argentina a partir de 1993, que continúa hasta la actualidad, y que llega a su punto culminante en 1995, cuando se alcanza el valor más alto de desempleo registrado en la historia del capitalismo argentino. Hecho éste que le valió para que se la conociera como la "hiperdesocupación", como una asociación inmediata con los valores extraordinarios que registrara la inflación en el año 1989, y que enmarca a estas situaciones en un carácter "fuera de lo normal", casi catastrófico

Kinetics of the anodic dissolution of iron in concentrated ionic media : Galvanostatic and potentiostatic measurements

The anodic dissolution of iron has been studied in concentrated aqueous media by determining potential/current curves using potentiostatic and galvanostatic techniques. The results indicate that the most likely value of Tafel slope in the range of pH from 0 to 5 is 2·3 (2RT/3F) for the anodic reaction. The agreement between the two techniques is good. Among the various mechanisms proposed for the reaction, the results are interpreted satisfactorily by means of the reaction scheme recently proposed by Bockris et al.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Kinetics of the spontaneous dissolution of iron in concentrated ionic media

The kinetics of the dissolution of polycrystalline iron in acid solutions has been studied. Perchloric acid in sodium perchlorate, hydrochloric acid in sodium chloride and nitric acid in sodium nitrate solutions were used, covering the range of pH between 0 and 6 at temperatures from 40 to 70°C. The rate of dissolution was followed by recording the activity of hydrogen ion in the solution, the corrosion potential being constant during the run. The kinetic constant for hydrogen-ion disappearance was used to calculate the corrosion current-density assuming that hydrogen-ion discharge on an iron surface follows a Tafel equation with a slope of 2·3(2RT/F). For sodium perchlorate solutions the corrosion current increases with pH (in the range 1–5) with δ log icorr/δpH = −1. For sodium chloride solutions the slope is close to −0·50. In the same range of pH the corrosion rate is greater in the order ClO4−, Cl−, NO3−. The results are interpreted in terms of recent information about the kinetics of the iron electrode.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Electrochemistry of solvated proton in dimethylsulphoxide : II. Kinetics and mechanism of the electrolytic evolution of hydrogen on iron

The kinetics of the electrolytic evolution of hydrogen on iron electrodes using solutions of HCl in DMSO has been investigated. The electrode reaction was studied within the temperature range from 20 to 45°C at various HCl concentrations, in the presence of an excess of potassium perchlorate. The mechanism interpreting the electrode reaction comprises as first step the simple solvated-hydrogen-ion discharge as rate-controlling followed probably by a hydrogen adatom combination process. The theoretical parameters derived from this mechanism coincide with the results obtained from steady as well as from non-steady measurements.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Kinetics and mechanism of the iron electrode in solutions of HCl in dimethylsulphoxide

The kinetics of polycrystalline iron electrodes has been investigated under different experimental conditions, employing solutions of hydrogen chloride in dimethylsulphoxide in the presence of KClO4 as supporting electrolyte. Anodic E/I curves exhibit active and passive regions, the former having a Tafel slope of 2RT/3F. At the lower cathodic polarizations, hydrogen discharge occurs and at higher, the electrodeposition of ferrous ion takes place; both reactions have Tafel slopes of 2RT/F. Other kinetic parameters obtained include the reaction orders, dependence of corrosion potential on HCl concentration, non-steady slopes from decay curves, experimental activation energy, etc. The interpretation of the reactions is given in terms of a consecutive reaction mechanism involving the participation of solvent ions. The reaction scheme is formally the same as already discussed for the iron electrode in aqueous solutions to explain the 2RT/3F anodic Tafel slope.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The diffusion of ferrocyanide and ferricyanide ions in aqueous solutions of potassium hydroxide

The diffusion of ferro- and ferricyanide ions in potassium hydroxide solutions has been studied with the rotating disk electrode between 24 and 50°C. The quotient Dη/T was satisfactorily constant and temperature-independent. A comparison with previous results obtained for solutions containing sodium hydroxide and potassium chloride as supporting electrolytes is made.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

On the anodic passivity of iron in molten potassium bisulphate

The electrochemical behaviour of pure iron anodes in molten KHSO4 at 250°C was studied. Typical passivity phenomena were observed under potentiostatic as well as galvanostatic runs. A transition time related to the onset of full passivity was determined. The passive film was studied by X-ray diffraction. Its average structure corresponded to Fe3O4. The mechanisms of passivation and corrosion of passive iron are discussed on the basis of behaviour of passive iron in aqueous systems.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Chemical evidence of hydrogen sorption processes on potential cycled gold electrodes

Transient activation of polycrystalline gold electrodes for the hydrogen electrode reaction, produced either through potentiostatic or potentiodynamic treatment, is related to the adsorption of H atoms and its penetration into the bulk. Evidence for H atoms results from the application of silver crystal decoration technique. Hydrogen-loaded activated gold electrodes in contact with a soluble silver salt solution yield silver deposits which can be studied through conventional voltammetric stripping. The increase in activation for the HER correlates with the increase in the voltammetric contribution of 0 electroadsorption peak assigned to the (110) crystallographic face of gold. The development of a faceted surface structure with preferred orientation in the direction of the less dense atomic arrangement apparently favours the penetration of hydrogen into the bulk metal.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Kinetics and mechanisms of electrochemical reactions on platinum with solutions of iodine-sodium-iodide in dimethylsulphoxide

The kinetics and mechanisms of the iodine and tri-iodide ion reduction and iodide and tri-iodide ion oxidation on platinum have been determined, from a study of the electrochemical kinetic behaviour of DMSO solutions containing an iodine/sodium-iodide ratio greater than one. The likely mechanisms are the same as those recently discussed for the iodine—sodium-iodide solutions in acetonitrile, and all comprise consecutive reaction schemes involving, for the processes in the anodic direction, an ion-plus-atom reaction as rate-determining step, and the reverse reaction for the cathodic processes.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The diffusion of ferrocyanide and ferricyanide ions in aqueous solutions of potassium hydroxide

The diffusion of ferro- and ferricyanide ions in potassium hydroxide solutions has been studied with the rotating disk electrode between 24 and 50°C. The quotient Dη/T was satisfactorily constant and temperature-independent. A comparison with previous results obtained for solutions containing sodium hydroxide and potassium chloride as supporting electrolytes is made.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta