Platinum inert electrode

The cell notation is Zn Zn2+1 Co3+, Co2+ Pt Note that a comma separates the half-cell components that are in the same phase. The symbol Pt is used to indicate the presence of an inert platinum electrode. A single vertical line separates Pt (a solid) from the components of the half-cell, which are in the liquid phase. 

The reduction half-reaction does not include a solid conductor of electrons, so an inert platinum electrode is used in this half-cell. The platinum electrode is chemically unchanged, so it does not appear in the chemical equation or half-reactions. However, it is included in the shorthand representation of the cell. 

In a standard hydrogen electrode, which is open to the atmosphere, hydrogen gas at 1 atm pressure bubbles over an inert platinum electrode. The electrode is immersed in a solution containing 1 mol/L H+ ions. 

E the introduction of different ligands in the amine complexes increases E according to the order I < CN < SCN < Br < Cl < NO2 [159, 160]. Finally, we mention the famous cisplatin, cis-Pt(NH3)Cl2, which is a very powerful cancer chemotherapy drug [161]. Its effect was discovered by Rosenberg [162] accidentally when he investigated the influence of electric field on living cells. He used supposedly inert platinum electrodes to study the suspension of live Escherichia coli bacteria. It was found that, as a consequence of dissolution of Pt, cisplatin was formed which had a devastating effect on the bacteria. 

The tendency of a system to accept or donate electrons is measured using an inert electrode (typically platinum). Electrons can pass from the system into this electrode, which is thus a half-cell. The Pt electrode is connected via a potentiomenter to another half-cell of known potential (usually, a saturated calomel electrode). All potentials are referred to the hydrogen half-cell ... 

The most common metal indicator electrode is platinum, which is relatively inert—it does not participate in many chemical reactions. Its purpose is simply to transmit electrons to or from species in solution. Gold electrodes are even more inert than Pt. Various types of carbon are used as indicator electrodes because the rates of many redox reactions on the carbon surface are fast. A metal electrode works best when its surface is large and clean. To clean the electrode, dip it briefly in hot 8 M HN03 and rinse with distilled water. 

Figure 9.5 Controlled-potential coulometry cell with a mercury pool working electrode. a, Platinum wire contact to mercury pool working electrode b, mercury pool working electrode c, reference electrode d, auxiliary electrode e, porous Vycor f, sample solution g, inert gas inlet h, stirrer i, reference electrode salt bridge j, clean mercury k, waste. [From Ref. 11, adapted with permission.]...

The phenomenon of formation of the EMF during the electrolysis is encountered not only with gas electrodes, but also with metal electrodes, e. g. the originally eleotromotively inert platinum electrode which acts as a cathode and is immersed in a zinc sulphate solution, becomes coated with a layer of metallic zinc and acquires the potential corresponding to the Zn/Zn++ system. 

Probably the most common solid electrode is platinum, although it dissolves anodically in some melts, for example in halides. The choice of gold and silver [86] is also frequently made. Graphite is very often used because it is cheap and can be obtained in a wide range of sizes and qualities. These electrodes can be used over long periods of time, and they have a wide electrochemical stability, both anodic and cathodic. Vanadium and molybdenum are also used in appropriate systems. Studies for the use of some inert anodes made of semiconducting ceramics have been made, especially for aluminum electrolysis [87],... 

When an aqueous solution of a weak acid, HA, in a suitable container is connected to the terminals of a direct current power source (through inert platinum electrodes), electrolysis takes place. At the cathode, where reduction or the gain of electrons occurs, water dissociates and the anion A is liberated (ignoring the hydronium ion H30+) ... 

Redox potential is measured using an inert platinum electrode, which acquires the electric potential Ef of the soil when placed into the soil or a soil suspension. This potential is measured relative to a reference electrode with a known potential, such as the calomel electrode (.Fcai), which has a potential of 0.248 V at 25°C. This potential has to be added to the measured value... 

The first reaction requires a copper anode, but the other two can be carried out at the surface of an inert platinum electrode. 

Every oxidation must be accompanied by a reduction (i.e., the electrons must have somewhere to go). So it is impossible to determine experimentally the potential of any single electrode. We therefore establish an arbitrary standard. The conventional reference electrode is the standard hydrogen electrode (SHE). This electrode contains a piece of metal electrolytically coated with a grainy black surface of inert platinum metal, immersed in a 1 MH+ solution. Hydrogen, H2, is bubbled at 1 atm pressure through a glass envelope over the platinized electrode (Figure 21-8). 

Another example of a redox electrode is a gas electrode such as the hydrogen electrode discussed above. In this system a constant concentration of molecular hydrogen is maintained in the electrolyte solution, which also contains the hydrogen ion H. In order to achieve these conditions, hydrogen gas at constant pressure is bubbled over the inert platinum electrode at the point where it contacts the solution (fig. 9.1). Other gas electrodes involve molecular oxygen and chlorine. 

Kovalenko and Tikonova (1980) used inert electrodes and discovered a correlation between the oscillations in the redox potential and the concentration changes in the B-Z reactants. The graphite and vitreous carbon electrodes were used to measure the concentration ratio of the redox forms of the catalyst metal ions while the concentration of bromate reduction products were measured by the inert platinum electrodes. 

The extent of reducing ion species present can be collectively measured as the Eh. Oxidation involves the loss of electrons, while the process of reduction can be viewed as the gaining of electrons. In order to maintain electrical neutrality overall, it is clear that the oxidation of one species must be accompanied by the reduction of another somewhere in the system hence, the concept of redox - the simultaneous occurrence of reduction and oxidation. In practice, a chemically inert electrode such as platinum or gold is used, which can transfer electrons to or from the environment. The potential developed is measured relative to a standard cell which itself is calibrated relative to the standard hydrogen electrode. Although measurement of Eh can be problematic, relatively stable measurements can be obtained using permanently installed electrodes of platinum or gold whereas spot measurements should be avoided due to unstable and... 

Anode reaction involves release of electrons. However, in this electrolysis there is no Ag(s) to go into solution. The electrode is platinum which is a very inert metal and does not readily... 

The measurements were performed with an usual setup for siuface-enhanced Raman spectroscopy The Raman spectra were measured with a Spex 1406 spectrometer, the samples were illmninated with a Spectroscopy Instruments argon ion laser (A = 514 nm, 30 mW) and the spectra were detected by a Princeton Instruments optical multichannel analyzer imder computer control. All experiments were performed in an electrochemical cell containing an inert platinum working electrode mechanically... 

Hydrogen gas is bubbled across the surlacc of a platinum electrode so that the concentration of the gas at the surface is constanl at constant temperature and constant partial pressure of hydrogen. Note that in this case the inert platinum electrode plays no direct role in the reaction but serves onh as a surface where elec iron transfer can occur. 

When a counter-electrode other than inert platinum electrode is used, it is necessary to confirm whether the electrochemical reaction occurring at the counter-electrode is as reversible as a platinum counter-electrode [25]. Sharon and coworkers [26] has studied the efficiency of three types of counterelectrodes (ITO, Pt and Platinum-coated ITO) in a PEC cell of configuration ... 

Chemically inert platinum, gold, and carbon indicator electrodes are frequently used to conduct electrons to or from species in solution. In contrast with chemically inert elements, silver participates in the reaction Ag + e Ag(5). 

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