On a homogeneous electrochemical reaction of prussian blue/everitt's salt system

Voltammetric, chronopotentiometric, and spectroelectrochemical studies qn the homogeneous-phase (single phase) reaction of Prussian blue (PB)/Everitt's salt (ES) system in KC1 aqueous solution were carried out as a model for understanding the homogeneous electrochemical reaction of manganese dioxide. Analytical results of voltammetric and chronopotentiometric studies on PB/ES system indicated that the electrode potential was represented by the empirical formula.</p

Electrochemistry of Redox Reaction II. On the Kinetic Equations for Chronopotentiometry

Basic kinetic equations of chronopotentiometric potential-time curves, in which the equations for reversible, quasi-reversible and irreversible electron transfer process appeared in special cases, were given and a chronopotentiometric method for determining kinetic parameters was proposed therefrom. The method was demonstrated for Fe(3+)/Fe(2+) redox reaction in acidic aqueous media. The limitations of the method and the double-layer charging effects on the potential-time curve were discussed. The extension of the method to more general electrode processes was also considered

Electrochemistry of Redox Reaction III. On the Kinetic Equations for Chronoamperometry

A basic kinetic equation of potential-step chronoamperometric current-time curve controlled by the rates of diffusion and electron transfer for a simple one-electron charge transfer reaction was given and various features of current-time curves were deduced from a theoretical treatment. The current-time equations for reversible and irreversible electron transfer processes appear as special cases with limited conditions of the equation reported in the present paper. And a potential-step chronoamperometric method to determine kinetic parameters from a current-time curve was proposed therefrom. The extension of a basic kinetic equation to more general multistep charge-transfer process was also considered

Measurement of High Temperature Thermodynamic Propertiesof Several Binary Alkali Silicate Glasses

The method for continuous measurement of the high temperature heat content, developed by W.Oelsen et al. and applied to the glasses by M.Tashiro, was examined and modified in some points. Relations between the temperature and heat contents referred to the standard temperature 25℃, were determined for the some glasses of R(2)O-SiO(2) system, and the specific heats as well as the entropies were calculated. Comparing the results, some views have been obtained relating to the effect of the species and content of alkali ions on the thermodynamic quantities of such glasses

Potential Sweep Voltammetry of Na(2)O-SiO(2) Glass Melt by Stationary Platinum Electrodes

Potential sweep voltammetries of Na(2)O·SiO(2) and Na(2)O·2SiO(2) at 730-1200°C were performed with the stationary platinum wire electrode and with the sweep rates of 40 and 120mV/sec. Although current-potential relation of Na(2)O . SiO(2) at 1200°C gave stationary S-shape pattern, those of the rest were transient modes with hysteresis. From the voltammetric considerations, a reversible oxygen electrode process where diffuion of free oxygen anion or silicate anion may be a rate-determining stage was tentatively proposed. Approximate estimations of decomposition voltage supported that a sole reaction process such as the decomposition of Na(2)O or indirect decomposition of SiO(2) in the melt was most probable

Electrochemistry of Redox Reaction I. On the Kinetic Equations for Rotating Disk Technique

An equation on the current-polarization voltage characteristics of single charge transfer redox reaction on a rotating disk electrode (RDE) was given and a curvefitting method to determine kinetic parameters from an observed polarization curve was proposed therefrom. The method was demonstrated for Fe(2+)/Fe(3+)redox reaction in acidic aqueous electrolyte on Pt-RDE and the limitation of the method was discussed. The extension of the method to multistep charge transfer reaction was also considered

Measurements of Decomposition Voltage of Na(2)O-SiO(2) System at Elevated Temperature by Commutator Technique

Decomposition voltages of Na(2)O (30-50 mole % )-SiO(2) binary system were estimated at the temperature range of 700~1200℃ by commutator technique. As the experimental procedure, relations between electrolytic current and resulting polarization potential without ohmic loss were observed by 20 cps mechanical commutator, using Pt|Na(2)O-SiO(2)|Pt electrochemical system. Experimental decomposition voltages determined from above relationship were the value of 1.5~2.0 V at the temperature beyond about 800℃ with comparatively less reproducibility. Further investigations on the decomposition reaction mechanisms were made in reference to both a series of reversible decomposition voltages derived from thermodynamic calculations on the several proposed decomposition reactions and chemical equilibrium in vitreous silicates