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The standard hydrogen electrode (SHE), with [ H +] = 1 M works thus at a pH = 0. At pH = 7, when [ H +] = 10 −7 M, the reduction potential of H + differs from zero because it depends on pH. Solving the Nernst equation for the half-reaction of reduction of two protons into hydrogen gas gives: 2 H + + 2 e − ⇌ H 2
Where k is a geometric constant (disk, k = 4; hemispherical, k =2π), n is the number of electrons involved in the reaction, F is the Faraday constant (96 485 C eq−1), a is the radius of the electroactive surface, D is the diffusion coefficient of the redox species (D ferrocene methanol = 7.8 × 10 −6 ; D ruthenium hexamine = 8.7 × 10 −6 ...
The data below tabulates standard electrode potentials (E°), in volts relative to the standard hydrogen electrode (SHE), at: Temperature 298.15 K (25.00 °C; 77.00 °F); Effective concentration (activity) 1 mol/L for each aqueous or amalgamated (mercury-alloyed) species;
The current at the working electrode is plotted versus the voltage at the working electrode to yield the cyclic voltammogram (see Figure 1). Cyclic voltammetry is generally used to study the electrochemical properties of an analyte in solution [2] [3] [4] [1] or of a molecule that is adsorbed onto the electrode.
Automotive spot welding electrodes supplement AWS D8.7: Automotive spot welding recommendations supplement AWS D8.8: Automotive arc welding (steel) AWS D8.9: Automotive spot weld testing AWS D8.14: Automotive arc welding (aluminum) AWS D9.1: Sheet metal welding AWS D10.10: Heating practices for pipe and tube AWS D10.11: Root pass welding for ...
The screen-printed electrodes (SPEs) are presented as a single device in which there are three different electrodes: [4] Working electrode. Their response is sensitive to the analyte concentration. Reference electrode. It allows the application of a known potential, which is independent of the analyte and other ions concentration. Its potential ...
To avoid possible ambiguities, the electrode potential thus defined can also be referred to as Gibbs–Stockholm electrode potential. In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of E for a half-cell reaction when it is written as a reduction.
Such rates provide insights into the structure and bonding in the analyte and the electrode. For example, the exchange current densities for platinum and mercury electrodes for reduction of protons differ by a factor of 10 10, indicative of the excellent catalytic properties of platinum. Owing to this difference, mercury is the preferred ...