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Electrodes non-aqueous

Three electrodes are necessary to overcome the fact that the potentials of most electrodes change when continuous current is passed (polarisation). In a two-electrode cell the measured voltage is the difference in potential between two changing individual electrode potentials. In these circumstances it is impossible to calculate the potential of any one electrode. Non-aqueous solvents cause problems in terms of solubility of the analyte and supporting electrolyte but principally problems arise because the resistance of the solution rises. This causes loss of potentiostatic control. The reference electrode may also become unstable. [Pg.225]

D. Ostrovskii, F. Ronci, B. Scrosati, R Jacobsson, A FTIR and Raman study of spontaneous reactions occurring at the liNiyCo(l-yX)2 electrode/non-aqueous electrolyte interface, J. Power Sources 2001,94, 183-188. [Pg.319]

Fig. 6.1. Cyclic voltammograms obtained for an as-deposited diamond electrode. Non aqueous supporting electrolyte- 0.5 M Et4BF4. Fig. 6.1. Cyclic voltammograms obtained for an as-deposited diamond electrode. Non aqueous supporting electrolyte- 0.5 M Et4BF4.
As indicator electrodes glass and antimony electrodes are commonly used, but it must be noted that in benzene-methanol solutions, a glass-antimony electrode pair may be used in which the glass electrode functions as reference electrode. Glass electrodes should not be maintained in non-aqueous solvents for long periods, as the hydration layer of the glass bulb may be impaired and the electrode will then cease to function satisfactorily. [Pg.589]

The polarographic determination of metal ions such as Al3 + which are readily hydrolysed can present problems in aqueous solution, but these can often be overcome by the use of non-aqueous solvents. Typical non-aqueous solvents, with appropriate supporting electrolytes shown in parentheses, include acetic acid (CH3C02Na), acetonitrile (LiC104), dimethylformamide (tetrabutyl-ammonium perchlorate), methanol (KCN or KOH), and pyridine (tetraethyl-ammonium perchlorate), In these media a platinum micro-electrode is employed in place of the dropping mercury electrode. [Pg.614]

Daikhin, double layer capacitance of solid at rough electrodes, 52 of the double layer, of non-aqueous solutions, 61... [Pg.627]

Murphy and Waynewright, and change of upthrust on emersed metal, as a method of measuring, 34 Nikitas, at the air-solution interface, 30 in non-aqueous solutions, 71 for a nonpolarizable electrode, 4... [Pg.640]

Reference electrodes for non-aqueous solvents are always troublesome because the necessary salt bridge may add considerable errors by undefined junction potentials. Leakage of components of the reference compartment, water in particular, into the working electrode compartment is a further problem. Whenever electrochemical cells of very small dimensions have to be designed, the construction of a suitable reference electrode system may be very difficult. Thus, an ideal reference electrode would be a simple wire introduced into the test cell. The usefulness of redox modified electrodes as reference electrodes in this respect has been studied in some detail... [Pg.80]

To overcome some of the problems associated with aqueous media, non-aqueous systems with cadmium salt and elemental sulfur dissolved in solvents such as DMSO, DMF, and ethylene glycol have been used, following the method of Baranski and Fawcett [48-50], The study of CdS electrodeposition on Hg and Pt electrodes in DMSO solutions using cyclic voltammetry (at stationary electrodes) and pulse polarography (at dropping Hg electrodes) provided evidence that during deposition sulfur is chemisorbed at these electrodes and that formation of at least a monolayer of metal sulfide is probable. Formation of the initial layer of CdS involved reaction of Cd(II) ions with the chemisorbed sulfur or with a pre-existing layer of metal sulfide. [Pg.93]

Electrochemical processes involving metals, such as metal ion discharge and metal atom ionization, can be studied without the complications of structural changes when electrodes of the molten metal (at elevated temperatures and in non-aqueous electrolytes) or of the metal s liquid amalgam are used instead of the solid metal. [Pg.299]

Other important alternate electrochemical methods under study for pCO rely on measuring current associated with the direct reduction of CO. The electrochemistry of COj in both aqueous and non-aqueous media has been documented for some time 27-29) interferences from more easily reduced species such as O2 as well as many commonly used inhalation anesthetics have made the direct amperometric approach difficult to implement. One recently described attempt to circumvent some of these interference problems employs a two cathode configuration in which one electrode is used to scrub the sample of O by exhaustive reduction prior to COj amperometry at the second electrode. The response time and sensitivity of the approach may prove to be adequate for blood ps applications, but the issue of interfering anesthetics must be addressed more thorou ly in order to make the technique a truly viable alternative to the presently used indirect potentiometric electrode. [Pg.55]

Many substituted Q/QH2 systems can also be used, e.g., the tetrachloroquin-hydrone electrode in a non-aqueous medium31. [Pg.60]

Their potentials in 0.1 N, lmolal, IN and saturated KC1 solutions are 0.3337, 0.2800, 0.2897 and 0.2415 V, respectively. The dilute types reach their equilibrium potentials more quickly and these potentials are less dependent on temperature the SCE has the advantage of being less sensitive to current flow (electrolysis). The AgCl-Ag electrodes are more compact, do not need a liquid function, which makes them exceedingly attractive for analysis in non-aqueous media, and support high temperatures. [Pg.63]

In fact, any type of titration can be carried out potentiometrically provided that an indicator electrode is applied whose potential changes markedly at the equivalence point. As the potential is a selective property of both reactants (titrand and titrant), notwithstanding an appreciable influence by the titration medium [aqueous or non-aqueous, with or without an ISA (ionic strength adjuster) or pH buffer, etc.] on that property, potentiometric titration is far more important than conductometric titration. Moreover, the potentiometric method has greater applicability because it is used not only for acid-base, precipitation, complex-formation and displacement titrations, but also for redox titrations. [Pg.99]

As in electroanalysis both ionic and possible electrode aspects are of major interest, both aspects of solutes in non-aqueous solvents have to be considered this can best be done by dividing the theory of the solutions concerned into two parts, viz. (1) the exchange of ionic particles (ionotropy), which leads to acid-base systems, and (2) the exchange of electrons only, which leads to redox systems. [Pg.248]

Whereas in many instances potentiometric non-aqueous titrations of acids can show anomalies24 depending on the type of solvents and/or electrodes (owing to preferential adsorption of ions, ion pairs or complexes on the highly polar surface of the indicator electrode, or even adherence of precipitates on the latter), conductometric non-aqueous titrations, in contrast, although often accompanied by precipitate formation30, are not hindered by such phenomena sometimes, just as in aqueous titrations, the conductometric end-point can even be based on precipitate formation34. [Pg.268]

Conductometric titrations. Van Meurs and Dahmen25-30,31 showed that these titrations are theoretically of great value in understanding the ionics in non-aqueous solutions (see pp. 250-251) in practice they are of limited application compared with the more selective potentiometric titrations, as a consequence of the low mobilities and the mutually less different equivalent conductivities of the ions in the media concerned. The latter statement is illustrated by Table 4.7108, giving the equivalent conductivities at infinite dilution at 25° C of the H ion and of the other ions (see also Table 2.2 for aqueous solutions). However, in practice conductometric titrations can still be useful, e.g., (i) when a Lewis acid-base titration does not foresee a well defined potential jump at an indicator electrode, or (ii) when precipitations on the indicator electrode hamper its potentiometric functioning. [Pg.301]

Electrodes of the first kind have only limited application to titration in non-aqueous media a well-known example is the use of a silver electrode in the determination of sulphides and/or mercaptans in petroleum products by titration in methanol-benzene (1 1) with methanolic silver nitrate as titrant. As an indicator electrode of the second kind the antimony pH electrode (or antimony/antimony trioxide electrode) may be mentioned its standard potential value depends on proton solvation in the titration medium chosen cf., the equilibrium reaction on p. 46). [Pg.304]

Among the membrane electrodes, the glass pH electrode is by far the most important pH electrode in non-aqueous media in fact, there seem no real limitations to its use, if proper handling is adopted. [Pg.304]


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See also in sourсe #XX -- [ Pg.58 ]




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Non-aqueous

Reference Electrodes for Non-Aqueous Solutions

Reporting Electrode Potentials in Non-Aqueous Solutions (IUPAC Recommendation)

The electrode polarization in non-aqueous systems

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